Pandas MultiIndex Tutorial.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Pandas MultiIndex Tutorial"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# What's Pandas?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Pandas is one of the most-used open source libraries for importing and analyzing data available in Python today. It provides convenient ways to import, view, split, apply, and combine array-like data. And not just convenient, but efficient, too. For example, Pandas' read_csv and to_csv functions are so efficient that the library is often imported just for this task instead of relying on the standard library alternative!\n",
    "\n",
    "The core value of the library, however, comes through several data structure options, primarily Series (for labeled, homogenously-typed, one-dimensional arrays)  and DataFrames (for labeled, potentially heterogeneously-typed, two-dimensional arrays)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# What's a DataFrame?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "DataFrames are two-dimensional, labeled data structures, with columns of potentially different types. You can think of it like a spreadsheet or SQL table, or a dict of Series objects. It is generally the most commonly used Pandas object. Like Series, DataFrame accepts many different kinds of input, including dicts, lists, lists of lists, Series, numpy arrays, other DataFrames, external data from CSVs, etc.\n",
    "\n",
    "The DataFrame has two core parts:  an index (row labels; look like columns, but aren't) and columns (data with headers)."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# What's an index?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The index of a DataFrame is a set (i.e. each element is only represented once) that consists of a label for each row. To be helpful, those labels should be not just unique, but also meaningful. By default, if no index is provided, the index will be a numbered range, starting from 0 (known as a range index).\n",
    "\n",
    "A more meaningful index, however, would be something that uniquely describes each row of your data in a way that will help you look things up. For example, in a list of transactions, the date-time might be most useful. Alternatively, in a grade book for a math class the name of the student might be most useful.\n",
    "\n",
    "The most confusing thing about understanding about Pandas' indexes at first (in my opinion) is how to interact with them. While they look exactly like columns, they're not referenced in the same way (learn more [here](https://pandas.pydata.org/pandas-docs/stable/indexing.html)). Understanding that, I personally find it most useful to think of an index in Pandas like a column that's in time-out and that just can't play with all the other columns.\n",
    " - Note: Another common way in which Pandas' indexes are misunderstood at first is by thinking of them in SQL-like terms. While that can be helpful if that's what you're familiar with, in practice (and for performance) Pandas' and SQL's indexes are quite different (see this [SO answer](https://stackoverflow.com/questions/42641018/pandas-column-indexing-for-searching) and [Pandas Under The Hood by Jeff Tratner](http://www.jeffreytratner.com/slides/pandas-under-the-hood-pydata-seattle-2015.pdf))."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# What is a MultiIndex DataFrame?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Pandas' multiindex DataFrames extend the DataFrames described above by enabling effective storage and manipulation of arbitrarily high dimension data in a 2-dimensional tabular structure. ((If that sentence doesn't make sense yet, don't worry - it should by the end of this tutorial.))\n",
    "\n",
    "While the displayed version of a multiindexed DataFrame doesn't appear to be much more than a prettily-organized regular DataFrame, it's actually a pretty powerful structure if the data warrants its use."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# When should you use one?"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "1. When a single column’s value isn’t enough to uniquely identify a row (e.g. multiple records on the same date means date alone isn’t a good index).\n",
    "2. When data is logically hierarchical - meaning that it has multiple dimensions or “levels.”\n",
    "\n",
    "Besides structure, multiindexes offer relatively easy in-memory retreival of complex data."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Realistic Demo Data"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For this tutorial we will work with a realistic case of when multiindex DataFrames can come in handy - a grocer's retail transactions."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Pandas version: 0.22.0'"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# Normally put all your import up top, but this cell was ugly in the midst of the intro paragraphs\n",
    "from typing import Any\n",
    "\n",
    "import numpy as np\n",
    "import pandas as pd\n",
    "\n",
    "display(f\"Pandas version: {pd.__version__}\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Note that this notebook is using the Pandas version above. There have been many changes to MultiIndex methods since 0.19, including major bug fixes. **It is STRONGLY recommended to use the latest version of Pandas, but at least version 0.21 is required for all of the techniques in this notebook to work as presented.**"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [],
   "source": [
    "# # Creates random mock data.\n",
    "# # Based on the UPCs found in upc_meta_data.csv and saves to data.csv\n",
    "# %run mocker.py"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
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       "  <tbody>\n",
       "    <tr>\n",
       "      <th>20</th>\n",
       "      <td>2018-07-14</td>\n",
       "      <td>Store 3</td>\n",
       "      <td>Beer</td>\n",
       "      <td>Lagers</td>\n",
       "      <td>702770081011</td>\n",
       "      <td>Omission - Gluten Free Lager - 6 Pack</td>\n",
       "      <td>128.64</td>\n",
       "      <td>12</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>101</th>\n",
       "      <td>2018-07-10</td>\n",
       "      <td>Store 3</td>\n",
       "      <td>Alcohol</td>\n",
       "      <td>Liqour</td>\n",
       "      <td>80480280024</td>\n",
       "      <td>Grey Goose - Imported Vodka - 750 mL Bottle</td>\n",
       "      <td>128.30</td>\n",
       "      <td>5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>68</th>\n",
       "      <td>2018-07-14</td>\n",
       "      <td>Store 1</td>\n",
       "      <td>Wine</td>\n",
       "      <td>Red</td>\n",
       "      <td>492130008399</td>\n",
       "      <td>Yellow Tail - Merlot - 750 mL Bottle</td>\n",
       "      <td>32.10</td>\n",
       "      <td>6</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>12</th>\n",
       "      <td>2018-07-16</td>\n",
       "      <td>Store 2</td>\n",
       "      <td>Beer</td>\n",
       "      <td>Ales</td>\n",
       "      <td>94922755711</td>\n",
       "      <td>Bowser Beer - Beefy Brown Ale - 6 Pack</td>\n",
       "      <td>99.40</td>\n",
       "      <td>10</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>58</th>\n",
       "      <td>2018-07-16</td>\n",
       "      <td>Store 1</td>\n",
       "      <td>Wine</td>\n",
       "      <td>Red</td>\n",
       "      <td>89744402585</td>\n",
       "      <td>Trapiche - Malbec - 750 mL Bottle</td>\n",
       "      <td>126.14</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>1</th>\n",
       "      <td>2018-07-11</td>\n",
       "      <td>Store 2</td>\n",
       "      <td>Beer</td>\n",
       "      <td>Ales</td>\n",
       "      <td>736920111112</td>\n",
       "      <td>Goose Island - Honkers Ale - 6 Pack</td>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>100</th>\n",
       "      <td>2018-07-10</td>\n",
       "      <td>Store 2</td>\n",
       "      <td>Alcohol</td>\n",
       "      <td>Liqour</td>\n",
       "      <td>80480280024</td>\n",
       "      <td>Grey Goose - Imported Vodka - 750 mL Bottle</td>\n",
       "      <td>231.30</td>\n",
       "      <td>9</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>59</th>\n",
       "      <td>2018-07-16</td>\n",
       "      <td>Store 3</td>\n",
       "      <td>Wine</td>\n",
       "      <td>Red</td>\n",
       "      <td>89744402585</td>\n",
       "      <td>Trapiche - Malbec - 750 mL Bottle</td>\n",
       "      <td>66.16</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>116</th>\n",
       "      <td>2018-07-11</td>\n",
       "      <td>Store 3</td>\n",
       "      <td>Alcohol</td>\n",
       "      <td>Liquor</td>\n",
       "      <td>674545000001</td>\n",
       "      <td>Don Julio - Tequila Blanco - 750 mL Bottle</td>\n",
       "      <td>102.04</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>77</th>\n",
       "      <td>2018-07-15</td>\n",
       "      <td>Store 3</td>\n",
       "      <td>Wine</td>\n",
       "      <td>Red</td>\n",
       "      <td>492130008399</td>\n",
       "      <td>Yellow Tail - Merlot - 750 mL Bottle</td>\n",
       "      <td>58.20</td>\n",
       "      <td>12</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "          Date    Store Category Subcategory       UPC EAN  \\\n",
       "20  2018-07-14  Store 3     Beer      Lagers  702770081011   \n",
       "101 2018-07-10  Store 3  Alcohol      Liqour   80480280024   \n",
       "68  2018-07-14  Store 1     Wine         Red  492130008399   \n",
       "12  2018-07-16  Store 2     Beer        Ales   94922755711   \n",
       "58  2018-07-16  Store 1     Wine         Red   89744402585   \n",
       "1   2018-07-11  Store 2     Beer        Ales  736920111112   \n",
       "100 2018-07-10  Store 2  Alcohol      Liqour   80480280024   \n",
       "59  2018-07-16  Store 3     Wine         Red   89744402585   \n",
       "116 2018-07-11  Store 3  Alcohol      Liquor  674545000001   \n",
       "77  2018-07-15  Store 3     Wine         Red  492130008399   \n",
       "\n",
       "                                     Description  Dollars  Units  \n",
       "20         Omission - Gluten Free Lager - 6 Pack   128.64     12  \n",
       "101  Grey Goose - Imported Vodka - 750 mL Bottle   128.30      5  \n",
       "68          Yellow Tail - Merlot - 750 mL Bottle    32.10      6  \n",
       "12        Bowser Beer - Beefy Brown Ale - 6 Pack    99.40     10  \n",
       "58             Trapiche - Malbec - 750 mL Bottle   126.14     14  \n",
       "1            Goose Island - Honkers Ale - 6 Pack   166.74     14  \n",
       "100  Grey Goose - Imported Vodka - 750 mL Bottle   231.30      9  \n",
       "59             Trapiche - Malbec - 750 mL Bottle    66.16      8  \n",
       "116   Don Julio - Tequila Blanco - 750 mL Bottle   102.04      4  \n",
       "77          Yellow Tail - Merlot - 750 mL Bottle    58.20     12  "
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df = pd.read_csv('data.csv', parse_dates=['Date'])\n",
    "df.sample(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Each row of data represents a sale of an item, but how do we set our index meaningfully? A numeric ID for each transaction would be fine, but it wouldn't tell us terribly much. Even the date of a transaction isn't useful by itself, since it's common for such a company to have many transactions on a given date (even at the same time). \n",
    "\n",
    "Instead, we will have to look at a combination of the available metadata to create a unique and meaningful index. At first glance, a combination of the date, the store, and the hierarchy of each item (Category > Subcategory > UPC) look like they might be enough to get us a unique index."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Setting and Manipulating MultiIndexes\n",
    "\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So let's take a look at how we can create our multiindex from our regular ol' DataFrame. We'll walk through the basics of setting, reordering, and resetting indexes, along with some useful tips/tricks. Then we can begin investigating our transaction data to learn about our sales and trends."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
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       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>736920111112</td>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>736920111112</td>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>736920111112</td>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
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      ],
      "text/plain": [
       "                                                                                  UPC EAN  \\\n",
       "Date       Store   Category Subcategory Description                                         \n",
       "2018-07-11 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack  736920111112   \n",
       "           Store 2 Beer     Ales        Goose Island - Honkers Ale - 6 Pack  736920111112   \n",
       "2018-07-10 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack  736920111112   \n",
       "\n",
       "                                                                             Dollars  \\\n",
       "Date       Store   Category Subcategory Description                                    \n",
       "2018-07-11 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Beer     Ales        Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                             Units  \n",
       "Date       Store   Category Subcategory Description                                 \n",
       "2018-07-11 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Beer     Ales        Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Set just like the index for a DataFrame...\n",
    "# ...except we give a list of column names instead of a single string column name\n",
    "df.set_index(['Date', 'Store', 'Category', 'Subcategory', 'Description'], inplace=True)\n",
    "df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Uh oh - it looks like we forgot to add the 'UPC EAN' column to our index, but don't worry - Pandas has us covered with extra set_index parameters for MultiIndexes:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
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       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <th>736920111112</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <th>736920111112</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <th>736920111112</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
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      ],
      "text/plain": [
       "                                                                                          Dollars  \\\n",
       "Date       Store   Category Subcategory Description                         UPC EAN                 \n",
       "2018-07-11 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112    35.68   \n",
       "           Store 2 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112   166.74   \n",
       "2018-07-10 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112    67.36   \n",
       "\n",
       "                                                                                          Units  \n",
       "Date       Store   Category Subcategory Description                         UPC EAN              \n",
       "2018-07-11 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112      4  \n",
       "           Store 2 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112     14  \n",
       "2018-07-10 Store 3 Beer     Ales        Goose Island - Honkers Ale - 6 Pack 736920111112      8  "
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# We can append a column to our existing index\n",
    "df.set_index('UPC EAN', append=True, inplace=True)\n",
    "df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "That's almost right, but we'd actually like 'Description' to show up after 'UPC EAN'. We have a couple of options to get things in the right order:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
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       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                          Dollars  \\\n",
       "Date       Store   Category Subcategory UPC EAN      Description                                    \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                                          Units  \n",
       "Date       Store   Category Subcategory UPC EAN      Description                                 \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Option 1 is the generalized solution to reorder the index levels\n",
    "# Note: We're not making an inplace change in this cell,\n",
    "#       but it's worth noting that this method doesn't have an inplace parameter.\n",
    "df.reorder_levels(order=['Date', 'Store', 'Category', 'Subcategory', 'UPC EAN', 'Description']).head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "reorder_levels() is useful, but it was a pain to have to type all five levels just two switch two. In cases like this we have a second, less verbose option:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "\n",
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       "    }\n",
       "\n",
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       "        text-align: right;\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
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       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                          Dollars  \\\n",
       "Date       Store   Category Subcategory UPC EAN      Description                                    \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                                          Units  \n",
       "Date       Store   Category Subcategory UPC EAN      Description                                 \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Option 2 just switches two index levels (a more common need than you'd think)\n",
    "# Note: This time we're doing an inplace change, but there's no parameter for this method either.\n",
    "df = df.swaplevel('Description', 'UPC EAN')\n",
    "df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Just when we thought we were done, it turns our we forgot to add the highest level of the product hierarchy - the Department - not just to our index, but to our DataFrame altogether. Luckily all of our records belong in the same Department, so here's a neat trick to add a new column with all the same values as a level in an existing index:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                     Dollars  \\\n",
       "Date       Store   Department Category Subcategory UPC EAN      Description                                    \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                                                     Units  \n",
       "Date       Store   Department Category Subcategory UPC EAN      Description                                 \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# A handy function to keep around for projects\n",
    "def add_constant_index_level(df: pd.DataFrame, value: Any, level_name: str):\n",
    "    \"\"\"Add a new level to an existing index where every row has the same, given value.\n",
    "    \n",
    "    Args:\n",
    "        df: Any existing pd.DataFrame.\n",
    "        value: Value to be placed in every row of the new index level.\n",
    "        level_name: Title of the new index level.\n",
    "    \n",
    "    Returns:\n",
    "        df with an additional, prepended index level.\n",
    "    \"\"\"\n",
    "    return pd.concat([df], keys=[value], names=[level_name])\n",
    "\n",
    "df = add_constant_index_level(df, \"Booooze\", \"Department\")\n",
    "df = df.reorder_levels(order=['Date', 'Store', 'Department', 'Category', 'Subcategory', 'UPC EAN', 'Description'])\n",
    "df.head(3)\n",
    "\n",
    "# # If we wanted to later drop that level\n",
    "# df.index = df.index.droplevel(level='Department')\n",
    "# df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now that our index is set the way we want it, what if we want to interact with those index levels? Here are a few helpful code snippets:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Index(['Ales', 'Lagers', 'Stouts', 'Malts', 'Red', 'White', 'Rose', 'Liqour',\n",
       "       'Liquor'],\n",
       "      dtype='object', name='Subcategory')"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# checking out their unique values, for a single level \n",
    "df.index.get_level_values('Subcategory').unique()\n",
    "\n",
    "# checking out their unique values, for combinations of multiple levels\n",
    "# See answer at https://stackoverflow.com/questions/39080555/pandas-get-level-values-for-multiple-columns"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Note the typo in \"Liquor\" above. Good thing we checked out unique values! Maybe someone can submit a pull request to fix this for me :)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "        text-align: right;\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
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       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Department</th>\n",
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       "      <th>Subcategory</th>\n",
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       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>80.01</td>\n",
       "      <td>9</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-12</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>78.30</td>\n",
       "      <td>10</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>37.75</td>\n",
       "      <td>5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-14</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>113.49</td>\n",
       "      <td>13</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>We changed this</th>\n",
       "      <td>45.05</td>\n",
       "      <td>5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-10</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>81.76</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>62.48</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>104.91</td>\n",
       "      <td>13</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>72.72</td>\n",
       "      <td>9</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-16</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>99.40</td>\n",
       "      <td>10</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>46.65</td>\n",
       "      <td>5</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-14</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>124.52</td>\n",
       "      <td>11</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                        Dollars  \\\n",
       "Date       Store   Department Category Subcategory UPC EAN      Description                                       \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 We changed this                           35.68   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                          166.74   \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 We changed this                           67.36   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                           80.01   \n",
       "2018-07-12 Store 3 Booooze    Beer     Ales        736920111112 We changed this                           78.30   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                           37.75   \n",
       "2018-07-14 Store 3 Booooze    Beer     Ales        736920111112 We changed this                          113.49   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                           45.05   \n",
       "2018-07-10 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack    81.76   \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack    62.48   \n",
       "2018-07-11 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   104.91   \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack    72.72   \n",
       "2018-07-16 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack    99.40   \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack    46.65   \n",
       "2018-07-14 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   124.52   \n",
       "\n",
       "                                                                                                        Units  \n",
       "Date       Store   Department Category Subcategory UPC EAN      Description                                    \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 We changed this                             4  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                            14  \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 We changed this                             8  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                             9  \n",
       "2018-07-12 Store 3 Booooze    Beer     Ales        736920111112 We changed this                            10  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                             5  \n",
       "2018-07-14 Store 3 Booooze    Beer     Ales        736920111112 We changed this                            13  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 We changed this                             5  \n",
       "2018-07-10 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack      8  \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack      8  \n",
       "2018-07-11 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     13  \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack      9  \n",
       "2018-07-16 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     10  \n",
       "           Store 3 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack      5  \n",
       "2018-07-14 Store 2 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     11  "
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Replace level values using rename\n",
    "# Note that this can be done using set_levels as well, but it's a pain\n",
    "df.rename(index={'Goose Island - Honkers Ale - 6 Pack': 'We changed this'}).head(15)\n",
    "\n",
    "# Replace np.nan level values\n",
    "# df.rename(index={np.nan: \"''\"}, inplace=True)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
       "<div>\n",
       "<style scoped>\n",
       "    .dataframe tbody tr th:only-of-type {\n",
       "        vertical-align: middle;\n",
       "    }\n",
       "\n",
       "    .dataframe tbody tr th {\n",
       "        vertical-align: top;\n",
       "    }\n",
       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
       "    }\n",
       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Desc.</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                     Dollars  \\\n",
       "Date       Store   Department Category Subcategory UPC EAN      Desc.                                          \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                                                     Units  \n",
       "Date       Store   Department Category Subcategory UPC EAN      Desc.                                       \n",
       "2018-07-11 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Rename index levels\n",
    "temp_df = df.copy()\n",
    "temp_df.index = df.index.set_names('Desc.', level='Description')\n",
    "temp_df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Understanding the MultiIndex Object"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Why is this section all the way down here? Because the MultiIndex object is scary looking if you're new to using them. Many guides to hierarchical data analysis using multiindex DataFrames start with DataFrame creation and manipulation using MultiIndex objects, which I think both hinders adoption and is not reflective of how a lot of DataFrames get created in practice. As a result, my explanation of MultiIndex objects is very basic, because there are lots of other great resources out there if you want to learn more. Here are my top two:\n",
    " * [Official guide](https://pandas.pydata.org/pandas-docs/stable/advanced.html?highlight=indexslice#hierarchical-indexing-multiindex)\n",
    " * [Python Data Science Handbook by Jake Vanderplas](https://jakevdp.github.io/PythonDataScienceHandbook/03.05-hierarchical-indexing.html#Methods-of-MultiIndex-Creation)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "MultiIndex(levels=[[2018-07-10 00:00:00, 2018-07-11 00:00:00, 2018-07-12 00:00:00, 2018-07-13 00:00:00, 2018-07-14 00:00:00, 2018-07-15 00:00:00, 2018-07-16 00:00:00], ['Store 1', 'Store 2', 'Store 3'], ['Booooze'], ['Alcohol', 'Beer', 'Wine'], ['Ales', 'Lagers', 'Liqour', 'Liquor', 'Malts', 'Red', 'Rose', 'Stouts', 'White'], [71250000140, 80432400630, 80480280024, 81248501095, 83783575217, 85000024218, 89744402585, 94922755711, 492130008399, 674545000001, 702770081011, 702770082018, 736920111112], ['Bowser Beer - Beefy Brown Ale - 6 Pack', 'Colt 45 - Malt Liquor - 6 Pack', 'Curious Beasts - Chardonnay - 750 mL Bottle', 'Dark Horse - S. Blanc Rose - 750 mL Bottle', 'Don Julio - Tequila Blanco - 750 mL Bottle', 'Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle', 'Goose Island - Honkers Ale - 6 Pack', 'Grey Goose - Imported Vodka - 750 mL Bottle', 'Omission - Gluten Free Lager - 6 Pack', 'Omission Pale Ale - Gluten Free Pale Ale - 6 Pack', 'Sierra Nevada Brewing Co. - Stout - 6 Pack', 'Trapiche - Malbec - 750 mL Bottle', 'Yellow Tail - Merlot - 750 mL Bottle']],\n",
       "           labels=[[1, 1, 0, 0, 2, 2, 4, 4, 0, 0, 1, 1, 6, 6, 4, 4, 5, 5, 2, 2, 4, 4, 0, 0, 6, 6, 2, 2, 4, 4, 3, 3, 0, 0, 1, 1, 5, 5, 0, 0, 1, 1, 6, 6, 5, 5, 2, 2, 6, 6, 1, 1, 5, 5, 3, 3, 2, 2, 6, 6, 5, 5, 0, 0, 1, 1, 4, 4, 4, 4, 3, 3, 0, 0, 6, 6, 5, 5, 2, 2, 3, 3, 2, 2, 0, 0, 1, 1, 4, 4, 6, 6, 0, 0, 3, 3, 2, 2, 1, 1, 0, 0, 5, 5, 2, 2, 1, 1, 6, 6, 2, 2, 6, 6, 0, 0, 1, 1, 5, 5, 2, 2, 3, 3, 1, 1, 4, 4, 5, 5, 0, 0], [2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 0, 2, 0, 2, 0, 2, 0, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 0, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 6, 6, 6, 6, 6, 6, 6, 6, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3], [12, 12, 12, 12, 12, 12, 12, 12, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 10, 10, 10, 10, 10, 10, 10, 10, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 0, 0, 0, 0, 0, 0, 0, 0, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 5, 5, 5, 5, 5, 5, 5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1], [6, 6, 6, 6, 6, 6, 6, 6, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 8, 8, 8, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1, 1, 1, 1, 1, 1, 1, 1, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5]],\n",
       "           names=['Date', 'Store', 'Department', 'Category', 'Subcategory', 'UPC EAN', 'Description'])"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "df.index"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Well that's gross looking...but don't be scared - it's actually not that hard to understand.\n",
    "\n",
    "**'levels'** is a list of lists, where each sublist represents all possible values in that index level. In other words, the 'levels' parameter reflects all possible unique values by level. For example, our first index level ('Date') has the possible values \\['2018-07-10', '2018-07-11', '2018-07-12', ...\\].\n",
    "\n",
    "* **Important Note:** When talking about a multiindex DataFrame (not the parameter for the MultiIndex object), we talk about the \"levels\" as the index \"columns.\" For example, the 'levels' of our df in a more general sense are 'Date', 'Store', 'Department', etc. Levels in this sense (and elsewhere in code) can also be referenced by number (e.g. 'Date' = 0 \\[read as 'level 0'\\], 'Store' = 1, 'Department' = 2, etc.).\n",
    "\n",
    "**'labels'** is also a list of lists, but here each sublist reflects all of the values that appear in the row of that index. In other words, each sublist in our labels is of the same length as the entire dataframe, and the value of each row is one of the possible values defined in our associated level (above). Looking again at our first index level ('Date'), we see values like \\[1, 1, 0, 0, 2, 2, 4, 4 ...\\]. There are just an enumerated representation of the options defined in our level, so 0 = '2018-07-10', 1 = '2018-07-11', 2 = '2018-07-12', 3 = '2018-07-13', etc.\n",
    "\n",
    "**'names'** is a list of the actual titles of each index level, in order of appearance from left to right."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "With that fresh understanding of the 'anatomy' of a MultiIndex, we can look at..."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Other Methods of Multiindex DataFrame Creation"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For the most part, the two references listed in the section above cover this topic well; however, a common use case that isn't covered in those guides is creating a multiindex DataFrame while reading from a csv:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "</style>\n",
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       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "      <th>Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Store</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">2018-07-11</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>35.68</td>\n",
       "      <td>4</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Store 2</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>166.74</td>\n",
       "      <td>14</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>67.36</td>\n",
       "      <td>8</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                          Dollars  \\\n",
       "Date       Store   Category Subcategory UPC EAN      Description                                    \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    35.68   \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack   166.74   \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack    67.36   \n",
       "\n",
       "                                                                                          Units  \n",
       "Date       Store   Category Subcategory UPC EAN      Description                                 \n",
       "2018-07-11 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      4  \n",
       "           Store 2 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack     14  \n",
       "2018-07-10 Store 3 Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      8  "
      ]
     },
     "execution_count": 13,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# We can set a MultiIndex while reading a csv by referencing columns to be used in the index by number\n",
    "pd.read_csv(\"data.csv\", index_col=[0, 1, 2, 3, 4, 5], skipinitialspace=True, parse_dates=['Date']).head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We'll review more advanced importing/exporting methods below."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# MultiIndex Columns (Multiple Column Levels)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "For a different view we can also create hierarchical column levels. We'll do this by introducting a new method: unstack(). This function \"pivots\" an index level to a new level of column labels whose inner-most level consists of the pivoted index labels. **Stack/unstack is one of the biggest reasons to use a MultiIndex, so it's work supplementing the examples here by checking out the [official docs on reshaping](https://pandas.pydata.org/pandas-docs/stable/reshaping.html#reshaping-by-stacking-and-unstacking).**\n",
    "\n",
    "With this new technique we can start actually investigating our data. For example, let's say we want to more easily compare sales of a product by store by day, we can unstack our 'Store' index level:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
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       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
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       "    <tr>\n",
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       "      <td>9.0</td>\n",
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       "      <td>NaN</td>\n",
       "      <td>161.15</td>\n",
       "      <td>345.07</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>11.0</td>\n",
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       "      <th rowspan=\"2\" valign=\"top\">2018-07-10</th>\n",
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       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
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       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
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       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
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       "      <td>201.72</td>\n",
       "      <td>318.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>8.0</td>\n",
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       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>174.72</td>\n",
       "      <td>NaN</td>\n",
       "      <td>104.86</td>\n",
       "      <td>14.0</td>\n",
       "      <td>NaN</td>\n",
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       "      <th>2018-07-12</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Wine</th>\n",
       "      <th>Red</th>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>95.16</td>\n",
       "      <td>NaN</td>\n",
       "      <td>75.60</td>\n",
       "      <td>12.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
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       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
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       "      <td>135.72</td>\n",
       "      <td>NaN</td>\n",
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       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
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       "      <td>476.64</td>\n",
       "      <td>NaN</td>\n",
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      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              174.72   \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                95.16   \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        221.04   \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         161.15   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  201.72   \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   89.76   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  415.68   \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          82.67   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        126.66   \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         345.07   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  318.80   \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              104.86   \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                75.60   \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  135.72   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  476.64   \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          75.74   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                14.0   \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                 12.0   \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            5.0   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     6.0   \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     6.0   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    12.0   \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.0   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-16 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           6.0  \n",
       "                               Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           11.0  \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "2018-07-16 Booooze    Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 7.0  \n",
       "2018-07-12 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                 10.0  \n",
       "2018-07-10 Booooze    Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    13.0  \n",
       "2018-07-15 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    12.0  \n",
       "2018-07-13 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.0  "
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "multi_col_lvl_df = df.unstack('Store')\n",
    "multi_col_lvl_df.sample(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The new view makes our comparison easier, but now it's a bit cluttered. Internally our multi-level columns are stored as tuples of the name values for each level, so we can easily fix the clutter by flattening the columns into a single level:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
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      "text/plain": [
       "                                                                                                           Dollars | Store 1  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                            \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                      NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle                NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                       NaN   \n",
       "\n",
       "                                                                                                           Dollars | Store 2  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                            \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                   231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle             172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                    168.06   \n",
       "\n",
       "                                                                                                           Dollars | Store 3  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                            \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                   128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle             278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                    204.12   \n",
       "\n",
       "                                                                                                           Units | Store 1  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                          \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                    NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle              NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                     NaN   \n",
       "\n",
       "                                                                                                           Units | Store 2  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                          \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                    9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle              5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                     6.0   \n",
       "\n",
       "                                                                                                           Units | Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                         \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                    5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle              8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                     7.0  "
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def flatten_cols(df: pd.DataFrame, delim: str = \"\"):\n",
    "    \"\"\"Flatten multiple column levels of the DataFrame into a one column level.\n",
    "\n",
    "    Args:\n",
    "        delim: the delimiter between the column values.\n",
    "\n",
    "    Returns:\n",
    "        A copy of the dataframe with the new column names.\n",
    "\n",
    "    \"\"\"\n",
    "    new_cols = [delim.join((col_lev for col_lev in tup if col_lev))\n",
    "                for tup in df.columns.values]\n",
    "    ndf = df.copy()\n",
    "    ndf.columns = new_cols\n",
    "\n",
    "    return ndf\n",
    "\n",
    "flattened_multi_col_df = flatten_cols(multi_col_lvl_df, \" | \").head(3)\n",
    "flattened_multi_col_df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "If later we want to undo that flattening it's just as simple:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
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       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "      <th></th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "                                                                                                          Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "                                                                                                          Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "\n",
       "                                                                                                                   \\\n",
       "                                                                                                          Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "                                                                                                          Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "                                                                                                          Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                                   \n",
       "                                                                                                          Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  "
      ]
     },
     "execution_count": 16,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def unflatten_cols(df: pd.DataFrame, delim: str = \"\"):\n",
    "    \"\"\"Unflatten a single column level into multiple column levels.\n",
    "\n",
    "    Args:\n",
    "        delim: the delimiter to split on to identify the multiple column values.\n",
    "\n",
    "    Returns:\n",
    "        A copy of the dataframe with the new column levels.\n",
    "\n",
    "    \"\"\"\n",
    "    new_cols = pd.MultiIndex.from_tuples([tuple(col.split(delim)) for col in df.columns])\n",
    "    ndf = df.copy()\n",
    "    ndf.columns = new_cols\n",
    "\n",
    "    return ndf\n",
    "\n",
    "unflatten_cols(flattened_multi_col_df, \" | \")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Importing/Exporting MultiIndex DataFrames"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We've already seen an example of reading a csv, but what if we want to save our multiindex DataFrame and then be able to reread it? How the stored files need to be accessed and by whom they need to be accessed will determine a lot. If everyone who needs access to the data is Python/Pandas savy, [pickling](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.Series.to_pickle.html) is fast and easy. If, however, other, not-tech-savy people will need to access the data, CSVs are a versitile storage medium. That said, it complicates our read_csv() a bit if we want to just dump out our multiindex. Revisiting our multi_col_lvl_df, where we have a multiindex DataFrame that has both multiple index levels and column levels, creates a difficult situation that requires getting to know as many as all 48 (yes, 48!) of read_csv's parameters."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "  <thead>\n",
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
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       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  "
      ]
     },
     "execution_count": 17,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Write our multi-column-level df\n",
    "multi_col_lvl_df.to_csv('multi_col_lvl_output.csv')\n",
    "\n",
    "# Reading it back in requires the header parameter\n",
    "read_multi_df = pd.read_csv('multi_col_lvl_output.csv', header=[0, 1], index_col=[0, 1, 2, 3, 4, 5],\n",
    "                            skipinitialspace=True, parse_dates=[0]).head(3)\n",
    "\n",
    "read_multi_df"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "By adding a header parameter to deal with our multiple column levels, on top of index_col for the setting of the index, this import looks good, but it required inspecting the csv for the column and row numbers (that's right - names won't work. Just to be sure everything worked, let's also check our dtypes:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Date: datetime64[ns]',\n",
       " 'Department: object',\n",
       " 'Category: object',\n",
       " 'Subcategory: object',\n",
       " 'UPC EAN: int64',\n",
       " 'Description: object']"
      ]
     },
     "execution_count": 18,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# A function to check our index level dtypes to aid this example\n",
    "def index_level_dtypes(df):\n",
    "    return [f\"{df.index.names[i]}: {df.index.get_level_values(n).dtype}\"\n",
    "            for i, n in enumerate(df.index.names)]\n",
    "\n",
    "index_level_dtypes(read_multi_df)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Looks good. However let's take a step back and look at what would have happened if we'd not parsed the dates and wanted to later change the dtype:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [
    {
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       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
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       "    <tr>\n",
       "      <th></th>\n",
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       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "data": {
      "text/plain": [
       "['Date: object',\n",
       " 'Department: object',\n",
       " 'Category: object',\n",
       " 'Subcategory: object',\n",
       " 'UPC EAN: int64',\n",
       " 'Description: object']"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# Reading it back iwithout parse_dates\n",
    "bad_dtype_df = pd.read_csv('multi_col_lvl_output.csv', header=[0, 1], index_col=[0, 1, 2, 3, 4, 5],\n",
    "                            skipinitialspace=True).head(3)\n",
    "\n",
    "display(bad_dtype_df)\n",
    "display(index_level_dtypes(bad_dtype_df))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Updating the dtypes of our index columns isn't going to be so simple, because our MultiIndex levels are immutable. To make any changes to the levels, we actually have to recreate the levels:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Date: datetime64[ns]',\n",
       " 'Department: object',\n",
       " 'Category: object',\n",
       " 'Subcategory: object',\n",
       " 'UPC EAN: int64',\n",
       " 'Description: object']"
      ]
     },
     "execution_count": 20,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "bad_dtype_df.index.set_levels([pd.to_datetime(bad_dtype_df.index.levels[0]), bad_dtype_df.index.levels[1],\n",
    "                               bad_dtype_df.index.levels[2], bad_dtype_df.index.levels[3],\n",
    "                               bad_dtype_df.index.levels[4], bad_dtype_df.index.levels[5]],\n",
    "                               inplace=True)\n",
    "index_level_dtypes(bad_dtype_df)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Alternatively we could reset just the 'Date' level, update its dtype, add it back to our index, and finally reorder our index:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['Date: datetime64[ns]',\n",
       " 'Department: object',\n",
       " 'Category: object',\n",
       " 'Subcategory: object',\n",
       " 'UPC EAN: int64',\n",
       " 'Description: object']"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "bad_dtype_df2 = bad_dtype_df.reset_index(level='Date')\n",
    "bad_dtype_df2['Date'] = pd.to_datetime(bad_dtype_df2['Date'],infer_datetime_format=True)\n",
    "bad_dtype_df2.set_index('Date', append=True, inplace=True)\n",
    "bad_dtype_df2 = (bad_dtype_df2.swaplevel('Date', 'Description')\n",
    "                              .swaplevel('Date', 'UPC EAN')\n",
    "                              .swaplevel('Date', 'Subcategory')\n",
    "                              .swaplevel('Date', 'Category')\n",
    "                              .swaplevel('Date', 'Department'))\n",
    "index_level_dtypes(bad_dtype_df2)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The moral of the story is, if you want to export and import complex multiindex DataFrames, learn read_csv's parameters well! The second moral is that, either of the above situations results in an awful lot of work.\n",
    "\n",
    "One alternative if the readability of the CSV by other users is important, is to simply reset the column levels and index levels before we write to a CSV and recreate them when we import. While it requires more steps and information is lost while in CSV form, it makes the code manipulations a lot easier:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/html": [
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       "\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                               Dollars  \\\n",
       "Store                                                                                          Store 1   \n",
       "Date       Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 2   \n",
       "Date       Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 3   \n",
       "Date       Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "\n",
       "                                                                                                 Units  \\\n",
       "Store                                                                                          Store 1   \n",
       "Date       Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 2   \n",
       "Date       Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                        \n",
       "Store                                                                                          Store 3  \n",
       "Date       Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  "
      ]
     },
     "execution_count": 22,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# a) restack the column levels,\n",
    "# b) drop any blanks the unstacking created, and then\n",
    "# c) reset the index so everything is a flat column again\n",
    "# d) output to csv\n",
    "multi_col_lvl_df.stack().dropna().reset_index().to_csv('index_removed_output.csv')\n",
    "\n",
    "# Reading it back in will require\n",
    "read_df = pd.read_csv(\"data.csv\", index_col=[0, 1, 2, 3, 4, 5], skipinitialspace=True, parse_dates=['Date'])\n",
    "read_df.unstack('Store').head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Still takes some work, but the code's a lot more straightforward."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "To this point we've really just been learning the basics of setting up our multiindex DataFrames, with a few neat tricks along the way. Now comes the fun part - actually interacting with those DataFrames to analyze our data."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Multiindex Math"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Math operations are as nearly as easy with multiindex DataFrames as with regular ones, but a whole lot more powerful. Let's say we want to calculate dollars per unit for each of our stores. That's as simple as:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "\n",
       "    .dataframe thead th {\n",
       "        text-align: right;\n",
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr style=\"text-align: right;\">\n",
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       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>33.62</td>\n",
       "      <td>39.85</td>\n",
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       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liquor</th>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>32.23</td>\n",
       "      <td>31.37</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"5\" valign=\"top\">Booooze</th>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liquor</th>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>28.01</td>\n",
       "      <td>29.16</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Wine</th>\n",
       "      <th>White</th>\n",
       "      <th>81248501095</th>\n",
       "      <th>Curious Beasts - Chardonnay - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>20.94</td>\n",
       "      <td>19.90</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>7.11</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.30</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>14.96</td>\n",
       "      <td>10.44</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>25.70</td>\n",
       "      <td>25.66</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Wine</th>\n",
       "      <th>Red</th>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>4.89</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.76</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-12</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Stouts</th>\n",
       "      <th>83783575217</th>\n",
       "      <th>Sierra Nevada Brewing Co. - Stout - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>10.61</td>\n",
       "      <td>7.81</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Wine</th>\n",
       "      <th>Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>9.01</td>\n",
       "      <td>NaN</td>\n",
       "      <td>8.27</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "Store                                                                                                      Store 1  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                  \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle      NaN   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle             NaN   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle             NaN   \n",
       "                      Wine     White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle            NaN   \n",
       "                               Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     7.11   \n",
       "                      Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack      NaN   \n",
       "                      Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle            NaN   \n",
       "2018-07-16 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                  4.89   \n",
       "2018-07-12 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack             NaN   \n",
       "2018-07-16 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     9.01   \n",
       "\n",
       "Store                                                                                                      Store 2  \\\n",
       "Date       Department Category Subcategory UPC EAN      Description                                                  \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    33.62   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           32.23   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           28.01   \n",
       "                      Wine     White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle          20.94   \n",
       "                               Red         89744402585  Trapiche - Malbec - 750 mL Bottle                      NaN   \n",
       "                      Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    14.96   \n",
       "                      Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          25.70   \n",
       "2018-07-16 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                   NaN   \n",
       "2018-07-12 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           10.61   \n",
       "2018-07-16 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                      NaN   \n",
       "\n",
       "Store                                                                                                      Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    39.85  \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           31.37  \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           29.16  \n",
       "                      Wine     White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle          19.90  \n",
       "                               Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     6.30  \n",
       "                      Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    10.44  \n",
       "                      Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          25.66  \n",
       "2018-07-16 Booooze    Wine     Red         492130008399 Yellow Tail - Merlot - 750 mL Bottle                  7.76  \n",
       "2018-07-12 Booooze    Beer     Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.81  \n",
       "2018-07-16 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     8.27  "
      ]
     },
     "execution_count": 23,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dollars_per_unit = multi_col_lvl_df['Dollars'] / multi_col_lvl_df['Units']\n",
    "dollars_per_unit.sample(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We just operated on all the pairwise sub column levels at the same time! Now we'd like this answer as columns back in our original DataFrame:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
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       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
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       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>25.70</td>\n",
       "      <td>25.66</td>\n",
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       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
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       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
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       "      <td>NaN</td>\n",
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       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
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       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>28.01</td>\n",
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      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0   \n",
       "\n",
       "                                                                                                          Dollars per Unit  \\\n",
       "Store                                                                                                              Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                          \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                    NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle              NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                     NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         25.70   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   34.40   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle          28.01   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         25.66  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   34.85  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle          29.16  "
      ]
     },
     "execution_count": 24,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Add a column level for our new measure\n",
    "dollars_per_unit.columns = pd.MultiIndex.from_product([['Dollars per Unit'], dollars_per_unit.columns])\n",
    "\n",
    "# Concat it with our original data\n",
    "pd.concat([multi_col_lvl_df, dollars_per_unit], axis='columns').head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "We can similarly apply functions to our multiindex DataFrame:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "metadata": {},
   "outputs": [
    {
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       "      <td>NaN</td>\n",
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       "      <td>NaN</td>\n",
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       "      <td>NaN</td>\n",
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      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               0.14k   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   0.06k   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                0.05k   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         0.23k   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   0.17k   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle          0.17k   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              0.08k   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   0.09k   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 0.08k   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          0.08k   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         0.13k   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   0.28k   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           0.2k   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              0.06k   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   0.14k   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 0.07k   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               0.18k   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          0.12k   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   0.04k   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                0.03k   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               0.01k   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   0.01k   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                0.01k   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         0.01k   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   0.01k   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle          0.01k   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              0.01k   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   0.01k   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 0.01k   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          0.01k   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle         0.01k  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle   0.01k  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle          0.01k  \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              0.01k  \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   0.01k  \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 0.01k  \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               0.01k  \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          0.01k  \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   0.01k  \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                0.01k  "
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Change our units to 000s for funsies\n",
    "multi_col_lvl_df.applymap(lambda x: np.nan if np.isnan(x) else str(round(x/1000, 2)) + \"k\").head(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Sorting"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Before we start slicing and filtering, it's important to sort out data to drastically improve efficiency. In some cases pandas will begin sorting for you by default in the latest versions, but other times you'll get an ugly and confusing lexsort warning (referencing the default lexographic sorting order).\n",
    "\n",
    "Sorting indexes works the exactly the same way for multiindex DataFrames as with regular DataFrames, but with some extra parameters to decide on:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "Sort by Date, then Department, then Category, etc.:\n"
     ]
    },
    {
     "data": {
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       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"10\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"10\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Beer</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>81.76</td>\n",
       "      <td>62.48</td>\n",
       "      <td>NaN</td>\n",
       "      <td>8.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>89.76</td>\n",
       "      <td>135.72</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>13.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>80.01</td>\n",
       "      <td>67.36</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>137.67</td>\n",
       "      <td>NaN</td>\n",
       "      <td>176.96</td>\n",
       "      <td>13.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Stouts</th>\n",
       "      <th>83783575217</th>\n",
       "      <th>Sierra Nevada Brewing Co. - Stout - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>78.40</td>\n",
       "      <td>119.90</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              137.67   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   56.88   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                46.30   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              81.76   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   89.76   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 80.01   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          78.40   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              62.48   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  135.72   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 67.36   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              176.96   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         119.90   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   37.80   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                34.56   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                13.0   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     8.0   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                 10.0   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     6.0   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   9.0   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.0   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0  \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    13.0  \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   8.0  \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                14.0  \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           10.0  \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     6.0  \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  6.0  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "Sort by Category, then Subcategory, then UPC EAN, then Description, then Date, then Deparment:\n"
     ]
    },
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       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
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       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-11</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>248.80</td>\n",
       "      <td>296.01</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
       "      <td>11.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>201.72</td>\n",
       "      <td>318.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>338.10</td>\n",
       "      <td>102.04</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
       "      <td>4.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-12</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>279.36</td>\n",
       "      <td>228.08</td>\n",
       "      <td>NaN</td>\n",
       "      <td>12.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>250.25</td>\n",
       "      <td>455.13</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>13.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>410.88</td>\n",
       "      <td>268.56</td>\n",
       "      <td>NaN</td>\n",
       "      <td>12.0</td>\n",
       "      <td>9.0</td>\n",
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       "    <tr>\n",
       "      <th>2018-07-13</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Alcohol</th>\n",
       "      <th>Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>432.74</td>\n",
       "      <td>185.75</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>5.0</td>\n",
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      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        248.80   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  201.72   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         338.10   \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        279.36   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  250.25   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         410.88   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  432.74   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        296.01   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  318.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         102.04   \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        228.08   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  455.13   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         268.56   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  185.75   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          10.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     6.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           10.0   \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          12.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     7.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           12.0   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    11.0   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "2018-07-11 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          11.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            4.0  \n",
       "2018-07-12 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           8.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    13.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            9.0  \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "Sort by Category, then Date only:\n"
     ]
    },
    {
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       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
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       "      <th>Liquor</th>\n",
       "      <th>674545000001</th>\n",
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       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>338.10</td>\n",
       "      <td>102.04</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
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       "      <td>NaN</td>\n",
       "      <td>410.88</td>\n",
       "      <td>268.56</td>\n",
       "      <td>NaN</td>\n",
       "      <td>12.0</td>\n",
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       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>177.00</td>\n",
       "      <td>430.50</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>14.0</td>\n",
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       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>161.15</td>\n",
       "      <td>345.07</td>\n",
       "      <td>NaN</td>\n",
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       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
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       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
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       "      <td>201.72</td>\n",
       "      <td>318.80</td>\n",
       "      <td>NaN</td>\n",
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       "      <td>268.52</td>\n",
       "      <td>NaN</td>\n",
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       "</div>"
      ],
      "text/plain": [
       "                                                                                                          Dollars  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         338.10   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         410.88   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         177.00   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         161.15   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  201.72   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  250.25   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  432.74   \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  227.82   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         102.04   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         268.56   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         430.50   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         345.07   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  318.80   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  455.13   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  185.75   \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  268.52   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           10.0   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           12.0   \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            5.0   \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     6.0   \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     7.0   \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    11.0   \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     6.0   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "2018-07-11 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            4.0  \n",
       "2018-07-12 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            9.0  \n",
       "2018-07-15 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           14.0  \n",
       "2018-07-16 Booooze    Alcohol  Liquor      674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           11.0  \n",
       "2018-07-10 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "2018-07-11 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "2018-07-12 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    13.0  \n",
       "2018-07-13 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0  \n",
       "2018-07-14 Booooze    Alcohol  Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     7.0  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# By default sort_index will sort all levels of the index,\n",
    "# first sorting the first index level, then secondarily sorting the second index level, and so on...\n",
    "sort1 = multi_col_lvl_df.copy()\n",
    "sort1.sort_index(inplace=True)\n",
    "print(\"\\nSort by Date, then Department, then Category, etc.:\")\n",
    "display(sort1.head(10))\n",
    "\n",
    "# ...but you can choose to starting from a different level...\n",
    "sort2 = multi_col_lvl_df.copy()\n",
    "sort2.sort_index(level='Category', inplace=True)\n",
    "print(\"\\nSort by Category, then Subcategory, then UPC EAN, then Description, then Date, then Deparment:\")\n",
    "display(sort2.head(10))\n",
    "\n",
    "# ...or even to only sort on specifc levels.\n",
    "sort3 = multi_col_lvl_df.copy()\n",
    "sort3.sort_index(level=['Category', 'Date'], sort_remaining=False, inplace=True)\n",
    "print(\"\\nSort by Category, then Date only:\")\n",
    "display(sort3.head(10))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Slicing, Filtering, and Querying"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "With the sorting out of the way we can begin searching our data by specific criteria. There is a fantastic guide about [understanding SettingwithCopyWarnings in Pandas](https://www.dataquest.io/blog/settingwithcopywarning/), so if you're unclear on the difference between a view and a copy, I suggest giving that a read first.\n",
    "\n",
    "Readers who have used Pandas for slicing previously will know that .loc is generally the preferred method of referencing cells in a DataFrame. The same type of syntax exists for multiindex Dataframes:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 27,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "View only rows in the 'Dollars' columns where the Category is 'Beer':\n"
     ]
    },
    {
     "data": {
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       "</style>\n",
       "<table border=\"1\" class=\"dataframe\">\n",
       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>81.76</td>\n",
       "      <td>62.48</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>104.91</td>\n",
       "      <td>72.72</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-14</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>124.52</td>\n",
       "      <td>113.68</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-15</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>88.77</td>\n",
       "      <td>119.47</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>99.40</td>\n",
       "      <td>46.65</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>101.79</td>\n",
       "      <td>107.58</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-13</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>103.59</td>\n",
       "      <td>142.44</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-15</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>139.23</td>\n",
       "      <td>40.50</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>47.55</td>\n",
       "      <td>108.48</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>80.01</td>\n",
       "      <td>67.36</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                               Dollars  \\\n",
       "Store                                                                                          Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                      \n",
       "2018-07-10 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN   \n",
       "2018-07-11 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN   \n",
       "2018-07-14 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN   \n",
       "2018-07-15 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN   \n",
       "2018-07-16 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN   \n",
       "2018-07-11 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN   \n",
       "2018-07-13 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN   \n",
       "2018-07-15 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN   \n",
       "2018-07-16 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN   \n",
       "2018-07-10 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack        NaN   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                      \n",
       "2018-07-10 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   81.76   \n",
       "2018-07-11 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack  104.91   \n",
       "2018-07-14 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack  124.52   \n",
       "2018-07-15 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   88.77   \n",
       "2018-07-16 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   99.40   \n",
       "2018-07-11 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          101.79   \n",
       "2018-07-13 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          103.59   \n",
       "2018-07-15 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          139.23   \n",
       "2018-07-16 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack           47.55   \n",
       "2018-07-10 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      80.01   \n",
       "\n",
       "                                                                                                        \n",
       "Store                                                                                          Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                     \n",
       "2018-07-10 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   62.48  \n",
       "2018-07-11 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   72.72  \n",
       "2018-07-14 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack  113.68  \n",
       "2018-07-15 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack  119.47  \n",
       "2018-07-16 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack   46.65  \n",
       "2018-07-11 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          107.58  \n",
       "2018-07-13 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          142.44  \n",
       "2018-07-15 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack           40.50  \n",
       "2018-07-16 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack          108.48  \n",
       "2018-07-10 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack      67.36  "
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    },
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\n",
      "View only rows in the 'Dollars' AND 'Store 1' column where the Category is 'Beer':\n"
     ]
    },
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       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Dollars</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-14</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-15</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-11</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-13</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-15</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-16</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Malts</th>\n",
       "      <th>71250000140</th>\n",
       "      <th>Colt 45 - Malt Liquor - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>2018-07-10</th>\n",
       "      <th>Booooze</th>\n",
       "      <th>Beer</th>\n",
       "      <th>Ales</th>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                               Dollars\n",
       "Store                                                                                          Store 1\n",
       "Date       Department Category Subcategory UPC EAN      Description                                   \n",
       "2018-07-10 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN\n",
       "2018-07-11 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN\n",
       "2018-07-14 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN\n",
       "2018-07-15 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN\n",
       "2018-07-16 Booooze    Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack     NaN\n",
       "2018-07-11 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN\n",
       "2018-07-13 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN\n",
       "2018-07-15 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN\n",
       "2018-07-16 Booooze    Beer     Malts       71250000140  Colt 45 - Malt Liquor - 6 Pack             NaN\n",
       "2018-07-10 Booooze    Beer     Ales        736920111112 Goose Island - Honkers Ale - 6 Pack        NaN"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "# A slicing helper. Works similarly to slicing in Python (e.g. list slicing),\n",
    "#                   but is inclusive of both the start and stop values.\n",
    "idx = pd.IndexSlice\n",
    "\n",
    "# View rows with a Category of Beer, but any Date, Department, Subcategory, UPC EAN, or Description\n",
    "# Only looking at Dollars columns\n",
    "print(\"View only rows in the 'Dollars' columns where the Category is 'Beer':\")\n",
    "display(sort3.loc[idx[:, :, 'Beer'], 'Dollars':'Dollars'].head(10))\n",
    "\n",
    "# If we just want to look at the Store 1 sub-column\n",
    "print(\"\\nView only rows in the 'Dollars' AND 'Store 1' column where the Category is 'Beer':\")\n",
    "display(sort3.loc[idx[:, :, 'Beer'], idx['Dollars', 'Store 1':'Store 1']].head(10))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Unfortunately the .loc syntax doesn't scale well to having many index levels. In order to select a values from a single level, .loc requires specifying ':' for every level that comes before. For the column names to show up for a single column you also need to use <name>:<name> syntax just to specify a single column. This can be incredibly annoying.\n",
    "    \n",
    "Instead, it is more common (and practical) to use df.xs (cross sections). df.xs allows us to filter our DataFrame to only those rows that match levels of our index we specify. We can choose an individual level or multiple levels easily:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
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       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
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       "    <tr>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"10\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>279.36</td>\n",
       "      <td>228.08</td>\n",
       "      <td>NaN</td>\n",
       "      <td>12.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>250.25</td>\n",
       "      <td>455.13</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>13.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>410.88</td>\n",
       "      <td>268.56</td>\n",
       "      <td>NaN</td>\n",
       "      <td>12.0</td>\n",
       "      <td>9.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"4\" valign=\"top\">Beer</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Ales</th>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>109.20</td>\n",
       "      <td>56.76</td>\n",
       "      <td>NaN</td>\n",
       "      <td>8.0</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>37.75</td>\n",
       "      <td>78.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>40.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>93.10</td>\n",
       "      <td>4.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Stouts</th>\n",
       "      <th>83783575217</th>\n",
       "      <th>Sierra Nevada Brewing Co. - Stout - 6 Pack</th>\n",
       "      <td>NaN</td>\n",
       "      <td>116.71</td>\n",
       "      <td>109.34</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>14.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
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       "      <td>69.29</td>\n",
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       "      <td>NaN</td>\n",
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       "    <tr>\n",
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      "text/plain": [
       "                                                                                               Dollars  \\\n",
       "Store                                                                                          Store 1   \n",
       "Department Category Subcategory UPC EAN      Description                                                 \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               40.12   \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   60.24   \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                95.16   \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle          93.94   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 2   \n",
       "Department Category Subcategory UPC EAN      Description                                                 \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        279.36   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  250.25   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         410.88   \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  109.20   \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                 37.75   \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         116.71   \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle          83.82   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 3   \n",
       "Department Category Subcategory UPC EAN      Description                                                 \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        228.08   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  455.13   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         268.56   \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   56.76   \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                 78.30   \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack               93.10   \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         109.34   \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   69.29   \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                75.60   \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle            NaN   \n",
       "\n",
       "                                                                                                 Units  \\\n",
       "Store                                                                                          Store 1   \n",
       "Department Category Subcategory UPC EAN      Description                                                 \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 4.0   \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     8.0   \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                 12.0   \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle            7.0   \n",
       "\n",
       "                                                                                                        \\\n",
       "Store                                                                                          Store 2   \n",
       "Department Category Subcategory UPC EAN      Description                                                 \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle          12.0   \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     7.0   \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle           12.0   \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     8.0   \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                   5.0   \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           11.0   \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle            6.0   \n",
       "\n",
       "                                                                                                        \n",
       "Store                                                                                          Store 3  \n",
       "Department Category Subcategory UPC EAN      Description                                                \n",
       "Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           8.0  \n",
       "                    Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle    13.0  \n",
       "                                674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            9.0  \n",
       "           Beer     Ales        702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     6.0  \n",
       "                                736920111112 Goose Island - Honkers Ale - 6 Pack                  10.0  \n",
       "                    Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                10.0  \n",
       "                    Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           14.0  \n",
       "           Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                    13.0  \n",
       "                                492130008399 Yellow Tail - Merlot - 750 mL Bottle                 10.0  \n",
       "                    Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle            NaN  "
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       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
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       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Subcategory</th>\n",
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       "      <th rowspan=\"4\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"4\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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       "    <tr>\n",
       "      <th>Rose</th>\n",
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       "      <th>Dark Horse - S. Blanc Rose - 750 mL Bottle</th>\n",
       "      <td>148.61</td>\n",
       "      <td>100.38</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>7.0</td>\n",
       "      <td>NaN</td>\n",
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       "      <th>White</th>\n",
       "      <th>81248501095</th>\n",
       "      <th>Curious Beasts - Chardonnay - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>293.16</td>\n",
       "      <td>278.60</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "      <td>14.0</td>\n",
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       "      <th rowspan=\"3\" valign=\"top\">2018-07-11</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th>Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>50.40</td>\n",
       "      <td>NaN</td>\n",
       "      <td>47.25</td>\n",
       "      <td>6.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rose</th>\n",
       "      <th>85000024218</th>\n",
       "      <th>Dark Horse - S. Blanc Rose - 750 mL Bottle</th>\n",
       "      <td>52.24</td>\n",
       "      <td>173.03</td>\n",
       "      <td>NaN</td>\n",
       "      <td>4.0</td>\n",
       "      <td>13.0</td>\n",
       "      <td>NaN</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>White</th>\n",
       "      <th>81248501095</th>\n",
       "      <th>Curious Beasts - Chardonnay - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>237.16</td>\n",
       "      <td>247.52</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>13.0</td>\n",
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       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">2018-07-12</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>60.24</td>\n",
       "      <td>NaN</td>\n",
       "      <td>69.29</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>13.0</td>\n",
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       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>95.16</td>\n",
       "      <td>NaN</td>\n",
       "      <td>75.60</td>\n",
       "      <td>12.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rose</th>\n",
       "      <th>85000024218</th>\n",
       "      <th>Dark Horse - S. Blanc Rose - 750 mL Bottle</th>\n",
       "      <td>93.94</td>\n",
       "      <td>83.82</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>6.0</td>\n",
       "      <td>NaN</td>\n",
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      "text/plain": [
       "                                                                                           Dollars  \\\n",
       "Store                                                                                      Store 1   \n",
       "Date       Department Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             56.88   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle          46.30   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   148.61   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             50.40   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle    52.24   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             60.24   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle          95.16   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle    93.94   \n",
       "\n",
       "                                                                                                    \\\n",
       "Store                                                                                      Store 2   \n",
       "Date       Department Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   100.38   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  293.16   \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   173.03   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  237.16   \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle    83.82   \n",
       "\n",
       "                                                                                                    \\\n",
       "Store                                                                                      Store 3   \n",
       "Date       Department Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             37.80   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle          34.56   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  278.60   \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             47.25   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  247.52   \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle             69.29   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle          75.60   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN   \n",
       "\n",
       "                                                                                             Units  \\\n",
       "Store                                                                                      Store 1   \n",
       "Date       Department Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               8.0   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle           10.0   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     11.0   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               6.0   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      4.0   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               8.0   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle           12.0   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      7.0   \n",
       "\n",
       "                                                                                                    \\\n",
       "Store                                                                                      Store 2   \n",
       "Date       Department Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      7.0   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0   \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     13.0   \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    11.0   \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      6.0   \n",
       "\n",
       "                                                                                                    \n",
       "Store                                                                                      Store 3  \n",
       "Date       Department Subcategory UPC EAN      Description                                          \n",
       "2018-07-10 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               6.0  \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle            6.0  \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0  \n",
       "2018-07-11 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle               7.0  \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  \n",
       "                      White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    13.0  \n",
       "2018-07-12 Booooze    Red         89744402585  Trapiche - Malbec - 750 mL Bottle              13.0  \n",
       "                                  492130008399 Yellow Tail - Merlot - 750 mL Bottle           10.0  \n",
       "                      Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  "
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       "                                                                     Dollars  \\\n",
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       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 2   \n",
       "Subcategory UPC EAN      Description                                           \n",
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       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
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       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  293.16   \n",
       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 3   \n",
       "Subcategory UPC EAN      Description                                           \n",
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       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle          34.56   \n",
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       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  278.60   \n",
       "\n",
       "                                                                       Units  \\\n",
       "Store                                                                Store 1   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               8.0   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle           10.0   \n",
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       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 2   \n",
       "Subcategory UPC EAN      Description                                           \n",
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       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      7.0   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0   \n",
       "\n",
       "                                                                              \n",
       "Store                                                                Store 3  \n",
       "Subcategory UPC EAN      Description                                          \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               6.0  \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            6.0  \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  \n",
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       "      <td>NaN</td>\n",
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       "    <tr>\n",
       "      <th>White</th>\n",
       "      <th>81248501095</th>\n",
       "      <th>Curious Beasts - Chardonnay - 750 mL Bottle</th>\n",
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       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "      <td>14.0</td>\n",
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       "  </tbody>\n",
       "</table>\n",
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      ],
      "text/plain": [
       "                                                                     Dollars  \\\n",
       "Store                                                                Store 1   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle             56.88   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle          46.30   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   148.61   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 2   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   100.38   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  293.16   \n",
       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 3   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle             37.80   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle          34.56   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  278.60   \n",
       "\n",
       "                                                                       Units  \\\n",
       "Store                                                                Store 1   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               8.0   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle           10.0   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     11.0   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                              \\\n",
       "Store                                                                Store 2   \n",
       "Subcategory UPC EAN      Description                                           \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      7.0   \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0   \n",
       "\n",
       "                                                                              \n",
       "Store                                                                Store 3  \n",
       "Subcategory UPC EAN      Description                                          \n",
       "Red         89744402585  Trapiche - Malbec - 750 mL Bottle               6.0  \n",
       "            492130008399 Yellow Tail - Merlot - 750 mL Bottle            6.0  \n",
       "Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  \n",
       "White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0  "
      ]
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
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       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
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       "  <tbody>\n",
       "    <tr>\n",
       "      <th>Beer</th>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>137.67</td>\n",
       "      <td>NaN</td>\n",
       "      <td>176.96</td>\n",
       "      <td>13.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"3\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rose</th>\n",
       "      <th>85000024218</th>\n",
       "      <th>Dark Horse - S. Blanc Rose - 750 mL Bottle</th>\n",
       "      <td>148.61</td>\n",
       "      <td>100.38</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>7.0</td>\n",
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       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                             Dollars  \\\n",
       "Store                                                                        Store 1   \n",
       "Category Subcategory UPC EAN      Description                                          \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack       137.67   \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle            56.88   \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle         46.30   \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle  148.61   \n",
       "\n",
       "                                                                                      \\\n",
       "Store                                                                        Store 2   \n",
       "Category Subcategory UPC EAN      Description                                          \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack          NaN   \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle              NaN   \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle           NaN   \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle  100.38   \n",
       "\n",
       "                                                                                      \\\n",
       "Store                                                                        Store 3   \n",
       "Category Subcategory UPC EAN      Description                                          \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack       176.96   \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle            37.80   \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle         34.56   \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                               Units  \\\n",
       "Store                                                                        Store 1   \n",
       "Category Subcategory UPC EAN      Description                                          \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack         13.0   \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle              8.0   \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle          10.0   \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle    11.0   \n",
       "\n",
       "                                                                                      \\\n",
       "Store                                                                        Store 2   \n",
       "Category Subcategory UPC EAN      Description                                          \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack          NaN   \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle              NaN   \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle           NaN   \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     7.0   \n",
       "\n",
       "                                                                                      \n",
       "Store                                                                        Store 3  \n",
       "Category Subcategory UPC EAN      Description                                         \n",
       "Beer     Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack         14.0  \n",
       "Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle              6.0  \n",
       "                     492130008399 Yellow Tail - Merlot - 750 mL Bottle           6.0  \n",
       "         Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     NaN  "
      ]
     },
     "metadata": {},
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    }
   ],
   "source": [
    "# We provide the level value, which by default searches the first index level ('Date')\n",
    "display(multi_col_lvl_df.xs('2018-07-12').head(10))\n",
    "\n",
    "# Here we're more specific because we want to search 'Category instead'\n",
    "display(multi_col_lvl_df.xs('Wine', level='Category').head(10))\n",
    "\n",
    "# To search for rows that match all of our level value requirements, use tuples\n",
    "display(multi_col_lvl_df.xs(('2018-07-10', 'Booooze', 'Wine'), level=['Date', 'Department', 'Category']).head(10))\n",
    "\n",
    "# Note that chaining .xs works, but is significantly less efficient\n",
    "display(multi_col_lvl_df.xs('2018-07-10', level='Date')\n",
    "                        .xs('Booooze', level='Department')\n",
    "                        .xs('Wine', level='Category')\n",
    "                        .head(10))\n",
    "\n",
    "# We can then use the column value filtering we're used to to filter rows as well\n",
    "cross_section_df = multi_col_lvl_df.xs(('2018-07-10', 'Booooze'), level=['Date', 'Department'])\n",
    "display(cross_section_df[cross_section_df['Dollars']['Store 1'] > 0].head(10))"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "That's a whole lot nicer of syntax than the .loc method, but it's still relatively verbose and requires separating out or index and column value filtering. Multiindex DataFrames also offer a lesser known method, df.query. Query is powerful for a few reasons:\n",
    "1. It can search both index levels and columns in the same query,\n",
    "2. Syntactically it's nicer, since it lets use write our query as short expressions,\n",
    "3. It's very efficient (depending on the chosen engine)\n",
    "\n",
    "The documentation has excellent [notes about the method](https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.query.html) and a nice [usage guide](https://pandas.pydata.org/pandas-docs/stable/indexing.html#multiindex-query-syntax) that are definitely worth a read but a couple of examples using our dataset:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "      <th></th>\n",
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       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
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       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
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       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
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       "      <th rowspan=\"4\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"4\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"4\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Rose</th>\n",
       "      <th>85000024218</th>\n",
       "      <th>Dark Horse - S. Blanc Rose - 750 mL Bottle</th>\n",
       "      <td>148.61</td>\n",
       "      <td>100.38</td>\n",
       "      <td>NaN</td>\n",
       "      <td>11.0</td>\n",
       "      <td>7.0</td>\n",
       "      <td>NaN</td>\n",
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       "      <th>White</th>\n",
       "      <th>81248501095</th>\n",
       "      <th>Curious Beasts - Chardonnay - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>293.16</td>\n",
       "      <td>278.60</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "      <td>14.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                    Dollars  \\\n",
       "Store                                                                                               Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle             56.88   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle          46.30   \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   148.61   \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                             \\\n",
       "Store                                                                                               Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle   100.38   \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  293.16   \n",
       "\n",
       "                                                                                                             \\\n",
       "Store                                                                                               Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle             37.80   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle          34.56   \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN   \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle  278.60   \n",
       "\n",
       "                                                                                                      Units  \\\n",
       "Store                                                                                               Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle               8.0   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle           10.0   \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle     11.0   \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle     NaN   \n",
       "\n",
       "                                                                                                             \\\n",
       "Store                                                                                               Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                           \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle               NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle            NaN   \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      7.0   \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0   \n",
       "\n",
       "                                                                                                             \n",
       "Store                                                                                               Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                          \n",
       "2018-07-10 Booooze    Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle               6.0  \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle            6.0  \n",
       "                               Rose        85000024218  Dark Horse - S. Blanc Rose - 750 mL Bottle      NaN  \n",
       "                               White       81248501095  Curious Beasts - Chardonnay - 750 mL Bottle    14.0  "
      ]
     },
     "execution_count": 29,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "multi_col_lvl_df.query(\"Date == '2018-07-10' and Category == 'Wine'\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "So why doesn't everyone always use df.query? It has two big drawbacks: \n",
    "1. It doesn't allow index or column names with spaces in the name. \n",
    "2. It can't deal with multiple column levels well.\n",
    "\n",
    "However, if you're used to working with SQL databases and/or willing to work within the above limitations, this is a powerful and fast option."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Updating Column Values"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now that we've learned a few ways to slice, filter, and query our data, what if we want to alter values in our dataframe? We can take advantage of the .loc method to replace values in place without creating a copy or, if temporarily copying our data isn't an issue (i.e. too big for memory) we can use the df.xs method with df.update:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 30,
   "metadata": {},
   "outputs": [
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       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"10\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"10\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Beer</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>We changed this</td>\n",
       "      <td>81.76</td>\n",
       "      <td>62.48</td>\n",
       "      <td>NaN</td>\n",
       "      <td>8.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>We changed this</td>\n",
       "      <td>89.76</td>\n",
       "      <td>135.72</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>13.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>We changed this</td>\n",
       "      <td>80.01</td>\n",
       "      <td>67.36</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>We changed this</td>\n",
       "      <td>NaN</td>\n",
       "      <td>176.96</td>\n",
       "      <td>13.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Stouts</th>\n",
       "      <th>83783575217</th>\n",
       "      <th>Sierra Nevada Brewing Co. - Stout - 6 Pack</th>\n",
       "      <td>We changed this</td>\n",
       "      <td>78.40</td>\n",
       "      <td>119.90</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.3</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                                   Dollars  \\\n",
       "Store                                                                                                              Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                          \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                    NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle              NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                     NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack             We changed this   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  We changed this   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                We changed this   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              We changed this   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         We changed this   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                            56.88   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                          46.3   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              81.76   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   89.76   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 80.01   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          78.40   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              62.48   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  135.72   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 67.36   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              176.96   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         119.90   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   37.80   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                34.56   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                13.0   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     8.0   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                 10.0   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     6.0   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   9.0   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.0   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0  \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    13.0  \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   8.0  \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                14.0  \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           10.0  \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     6.0  \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  6.0  "
      ]
     },
     "execution_count": 30,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "updated_df = multi_col_lvl_df.copy()\n",
    "updated_df.loc[idx[:, :, 'Beer'], idx['Dollars', 'Store 1':'Store 1']] = \"We changed this\"\n",
    "updated_df.head(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "The above syntax works well for immutable values, but you'll get an error if you try the same thing for a mutable value, like a list. To my knowledge the only way to set values in a DataFrame to a mutable object is one cell at a time, so doing multiple replacements requires iterrows:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 31,
   "metadata": {},
   "outputs": [],
   "source": [
    "# # Note: If the column we're changing's type isn't already object,\n",
    "# # we need to change it or the value relpacements below will error.\n",
    "# updated_df['Dollars']['Store 1'] = updated_df['Dollars']['Store 1'].astype(object)\n",
    "\n",
    "# # Loop through rows, replacing single values\n",
    "# # Only necessary if the new assigned value is mutable\n",
    "# # Code below currently not working when there are multiple column levels, but works with one column level\n",
    "# for index, row in updated_df.loc[idx[:, :, 'Beer'], idx['Dollars', 'Store 1':'Store 1']].iterrows():\n",
    "#     updated_df.at[index, idx['Dollars', 'Store 1':'Store 1']] = [\"We\", \"changed\", \"this\"]\n",
    "\n",
    "# updated_df.head(3)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Alternatively, using df.xs and then df.update instead of the full .loc is a little bit more understandable in my option. For example, the following code does the same as the code two cells above (except that it requires a copy):"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 32,
   "metadata": {},
   "outputs": [
    {
     "data": {
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       "  <thead>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th colspan=\"3\" halign=\"left\">Dollars</th>\n",
       "      <th colspan=\"3\" halign=\"left\">Units</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th>Store</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "      <th>Store 1</th>\n",
       "      <th>Store 2</th>\n",
       "      <th>Store 3</th>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Date</th>\n",
       "      <th>Department</th>\n",
       "      <th>Category</th>\n",
       "      <th>Subcategory</th>\n",
       "      <th>UPC EAN</th>\n",
       "      <th>Description</th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "      <th></th>\n",
       "    </tr>\n",
       "  </thead>\n",
       "  <tbody>\n",
       "    <tr>\n",
       "      <th rowspan=\"10\" valign=\"top\">2018-07-10</th>\n",
       "      <th rowspan=\"10\" valign=\"top\">Booooze</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Alcohol</th>\n",
       "      <th>Liqour</th>\n",
       "      <th>80480280024</th>\n",
       "      <th>Grey Goose - Imported Vodka - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>231.30</td>\n",
       "      <td>128.30</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>5.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Liquor</th>\n",
       "      <th>80432400630</th>\n",
       "      <th>Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>172.00</td>\n",
       "      <td>278.80</td>\n",
       "      <td>NaN</td>\n",
       "      <td>5.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>674545000001</th>\n",
       "      <th>Don Julio - Tequila Blanco - 750 mL Bottle</th>\n",
       "      <td>NaN</td>\n",
       "      <td>168.06</td>\n",
       "      <td>204.12</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>7.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"5\" valign=\"top\">Beer</th>\n",
       "      <th rowspan=\"3\" valign=\"top\">Ales</th>\n",
       "      <th>94922755711</th>\n",
       "      <th>Bowser Beer - Beefy Brown Ale - 6 Pack</th>\n",
       "      <td>We ALSO changed this</td>\n",
       "      <td>81.76</td>\n",
       "      <td>62.48</td>\n",
       "      <td>NaN</td>\n",
       "      <td>8.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>702770082018</th>\n",
       "      <th>Omission Pale Ale - Gluten Free Pale Ale - 6 Pack</th>\n",
       "      <td>We ALSO changed this</td>\n",
       "      <td>89.76</td>\n",
       "      <td>135.72</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "      <td>13.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>736920111112</th>\n",
       "      <th>Goose Island - Honkers Ale - 6 Pack</th>\n",
       "      <td>We ALSO changed this</td>\n",
       "      <td>80.01</td>\n",
       "      <td>67.36</td>\n",
       "      <td>NaN</td>\n",
       "      <td>9.0</td>\n",
       "      <td>8.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Lagers</th>\n",
       "      <th>702770081011</th>\n",
       "      <th>Omission - Gluten Free Lager - 6 Pack</th>\n",
       "      <td>We ALSO changed this</td>\n",
       "      <td>NaN</td>\n",
       "      <td>176.96</td>\n",
       "      <td>13.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>14.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>Stouts</th>\n",
       "      <th>83783575217</th>\n",
       "      <th>Sierra Nevada Brewing Co. - Stout - 6 Pack</th>\n",
       "      <td>We ALSO changed this</td>\n",
       "      <td>78.40</td>\n",
       "      <td>119.90</td>\n",
       "      <td>NaN</td>\n",
       "      <td>7.0</td>\n",
       "      <td>10.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th rowspan=\"2\" valign=\"top\">Wine</th>\n",
       "      <th rowspan=\"2\" valign=\"top\">Red</th>\n",
       "      <th>89744402585</th>\n",
       "      <th>Trapiche - Malbec - 750 mL Bottle</th>\n",
       "      <td>56.88</td>\n",
       "      <td>NaN</td>\n",
       "      <td>37.80</td>\n",
       "      <td>8.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
       "    </tr>\n",
       "    <tr>\n",
       "      <th>492130008399</th>\n",
       "      <th>Yellow Tail - Merlot - 750 mL Bottle</th>\n",
       "      <td>46.3</td>\n",
       "      <td>NaN</td>\n",
       "      <td>34.56</td>\n",
       "      <td>10.0</td>\n",
       "      <td>NaN</td>\n",
       "      <td>6.0</td>\n",
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       "  </tbody>\n",
       "</table>\n",
       "</div>"
      ],
      "text/plain": [
       "                                                                                                                        Dollars  \\\n",
       "Store                                                                                                                   Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                               \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle                         NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle                   NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle                          NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack             We ALSO changed this   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  We ALSO changed this   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                We ALSO changed this   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              We ALSO changed this   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         We ALSO changed this   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                                 56.88   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                               46.3   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        231.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  172.00   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         168.06   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              81.76   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack   89.76   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 80.01   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack          78.40   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 3   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle        128.30   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle  278.80   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle         204.12   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack              62.48   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack  135.72   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                 67.36   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack              176.96   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack         119.90   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                   37.80   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                34.56   \n",
       "\n",
       "                                                                                                            Units  \\\n",
       "Store                                                                                                     Store 1   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           NaN   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     NaN   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            NaN   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                NaN   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     NaN   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   NaN   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                13.0   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            NaN   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     8.0   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                 10.0   \n",
       "\n",
       "                                                                                                                   \\\n",
       "Store                                                                                                     Store 2   \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                 \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           9.0   \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     5.0   \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            6.0   \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0   \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack     6.0   \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   9.0   \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                 NaN   \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack            7.0   \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     NaN   \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  NaN   \n",
       "\n",
       "                                                                                                                   \n",
       "Store                                                                                                     Store 3  \n",
       "Date       Department Category Subcategory UPC EAN      Description                                                \n",
       "2018-07-10 Booooze    Alcohol  Liqour      80480280024  Grey Goose - Imported Vodka - 750 mL Bottle           5.0  \n",
       "                               Liquor      80432400630  Glenlivet - 12 Year Scotch Whisky - 750 mL Bottle     8.0  \n",
       "                                           674545000001 Don Julio - Tequila Blanco - 750 mL Bottle            7.0  \n",
       "                      Beer     Ales        94922755711  Bowser Beer - Beefy Brown Ale - 6 Pack                8.0  \n",
       "                                           702770082018 Omission Pale Ale - Gluten Free Pale Ale - 6 Pack    13.0  \n",
       "                                           736920111112 Goose Island - Honkers Ale - 6 Pack                   8.0  \n",
       "                               Lagers      702770081011 Omission - Gluten Free Lager - 6 Pack                14.0  \n",
       "                               Stouts      83783575217  Sierra Nevada Brewing Co. - Stout - 6 Pack           10.0  \n",
       "                      Wine     Red         89744402585  Trapiche - Malbec - 750 mL Bottle                     6.0  \n",
       "                                           492130008399 Yellow Tail - Merlot - 750 mL Bottle                  6.0  "
      ]
     },
     "execution_count": 32,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "updated_df = multi_col_lvl_df.copy()\n",
    "\n",
    "df2 = updated_df.xs('Beer', level='Category', drop_level=False).copy()  # .copy() is to avoid SettingwithCopyWarning\n",
    "df2[idx['Dollars', 'Store 1']] = \"We ALSO changed this\"\n",
    "\n",
    "updated_df.update(df2, join=\"left\", overwrite=True, filter_func=None, raise_conflict=False)\n",
    "updated_df.head(10)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Display options"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 33,
   "metadata": {},
   "outputs": [],
   "source": [
    "pd.set_option('display.multi_sparse', True)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# That's all, folks!"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Hopefully this guide has been a gentle and practical tutorial on multiindex DataFrames in Pandas. If you find any errors, material ommissions, or topics that could just be explained more clearly, please submit leave a comment or better yet, a pull request!\n",
    "\n",
    "To continue your learning, find a list of my top picks for Pandas resources - generally and specifically for MultiIndexes. Of particular note is the [Official list of available methods for MultiIndexes](https://pandas.pydata.org/pandas-docs/version/0.22/generated/pandas.MultiIndex.html), which has a full listing of all the available methods (many not listed here). **This link is specifically for Pandas version 0.22, because, for some reason, the list in future versions excludes a lot of still valuable methods!** What's more, this list provides the ONLY explanation for some methods, since many MultiIndex methods lack even the most basic of docstrings."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Resources"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "**Official MultiIndex References**\n",
    " * [Official MultiIndex / Advanced Indexing Tutorial](https://pandas.pydata.org/pandas-docs/stable/advanced.html?highlight=indexslice#hierarchical-indexing-multiindex)\n",
    " * [Official list of available methods for MultiIndexes](https://pandas.pydata.org/pandas-docs/version/0.22/generated/pandas.MultiIndex.html)\n",
    " \n",
    "**Other MultiIndex Tutorials**\n",
    " * [Official Reshaping by Stacking and Unstacking Tutorial](https://pandas.pydata.org/pandas-docs/stable/reshaping.html#reshaping-by-stacking-and-unstacking)\n",
    " * [Hierarchical indices, groupby and pandas by DataCamp](https://www.datacamp.com/community/tutorials/pandas-multi-index)\n",
    " * [Python Data Science Handbook by Jake Vanderplas](https://jakevdp.github.io/PythonDataScienceHandbook/03.05-hierarchical-indexing.html#Methods-of-MultiIndex-Creation)\n",
    " * [MultiIndex slicing by Nelson](https://www.somebits.com/~nelson/pandas-multiindex-slice-demo.html)\n",
    " * [Pandas examples and cookbook by Eric Neilsen, Jr.](http://ehneilsen.net/notebook/pandasExamples/pandas_examples.html)\n",
    " \n",
    "**General Pandas Tutorials**\n",
    " * [Official 10 Minutes to Pandas Tutorial](https://pandas.pydata.org/pandas-docs/stable/10min.html)\n",
    " * [Official Pandas Cheat Sheet](https://pandas.pydata.org/Pandas_Cheat_Sheet.pdf)\n",
    " * [Official Indexing and Selecting Data Tutorial](https://pandas.pydata.org/pandas-docs/stable/indexing.html)\n",
    " * [Understanding SettingwithCopyWarning in pandas by DataQuest](https://www.dataquest.io/blog/settingwithcopywarning/)\n",
    " \n",
    "**Pandas Operations and Efficiency**\n",
    " * [A Beginner’s Guide to Optimizing Pandas Code for Speed by Sofia Heisler](https://engineering.upside.com/a-beginners-guide-to-optimizing-pandas-code-for-speed-c09ef2c6a4d6)\n",
    " * [Using pandas with large data by DataQuest](https://www.dataquest.io/blog/pandas-big-data/)\n",
    " * [Pandas Under The Hood by Jeff Tratner](http://www.jeffreytratner.com/slides/pandas-under-the-hood-pydata-seattle-2015.pdf)\n",
    " * [Pandas 2.0 Internals: Data structure changes by Wes McKinney](https://pandas-dev.github.io/pandas2/internal-architecture.html)\n"
   ]
  }
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