test_collection.py

from __future__ import annotations

import fnmatch
import io
import operator
import pickle
from datetime import datetime, timedelta
from operator import add

import dask
import dask.array as da
import numpy as np
import pandas as pd
import pytest
from dask.dataframe._compat import PANDAS_GE_210, PANDAS_GE_220
from dask.dataframe.utils import UNKNOWN_CATEGORIES
from dask.utils import M

from dask_expr import (
    DataFrame,
    Series,
    expr,
    from_dict,
    from_pandas,
    is_scalar,
    isna,
    optimize,
    to_datetime,
    to_numeric,
    to_timedelta,
)
from dask_expr._expr import Filter, OpAlignPartitions, ToFrame, are_co_aligned
from dask_expr._reductions import Len
from dask_expr._shuffle import Shuffle
from dask_expr.datasets import timeseries
from dask_expr.io import FromPandas
from dask_expr.tests._util import _backend_library, assert_eq, xfail_gpu

# Set DataFrame backend for this module
pd = _backend_library()


@pytest.fixture
def pdf():
    pdf = pd.DataFrame({"x": range(100)})
    pdf["y"] = pdf.x // 7  # Not unique; duplicates span different partitions
    yield pdf


@pytest.fixture
def df(pdf):
    yield from_pandas(pdf, npartitions=10)


def test_del(pdf, df):
    pdf = pdf.copy()

    # Check __delitem__
    del pdf["x"]
    del df["x"]
    assert_eq(pdf, df)


@pytest.mark.parametrize("verbose", (True, False, None))
@pytest.mark.parametrize("buf", (None, io.StringIO))
@pytest.mark.parametrize("memory_usage", (True, False, None))
def test_info(df, verbose, buf, memory_usage):
    if buf is not None:
        buf = buf()
    kwargs = {
        k: v
        for k, v in (("verbose", verbose), ("buf", buf), ("memory_usage", memory_usage))
        if v is not None
    }

    ret = df.info(**kwargs)

    if buf and not verbose and not memory_usage:
        expected = (
            "<class 'dask_expr.DataFrame'>\n"
            "Columns: 2 entries, x to y\n"
            "dtypes: int64(2)"
        )
        assert buf.getvalue() == expected
    elif buf and verbose and not memory_usage:
        expected = (
            "<class 'dask_expr.DataFrame'>\n"
            "RangeIndex: 100 entries, 0 to 99\n"
            "Data columns (total 2 columns):\n"
            " #   Column  Non-Null Count  Dtype\n"
            "---  ------  --------------  -----\n"
            " 0   x       100 non-null      int64\n"
            " 1   y       100 non-null      int64\n"
            "dtypes: int64(2)"
        )
        assert buf.getvalue() == expected
    elif buf and not verbose and memory_usage:
        expected = (
            "<class 'dask_expr.DataFrame'>\n"
            "Columns: 2 entries, x to y\n"
            "dtypes: int64(2)\n"
            "memory usage: *\n"
        )
        assert fnmatch.fnmatch(buf.getvalue(), expected)
    elif all((buf, verbose, memory_usage)):
        expected = (
            "<class 'dask_expr.DataFrame'>\n"
            "RangeIndex: 100 entries, 0 to 99\n"
            "Data columns (total 2 columns):\n"
            " #   Column  Non-Null Count  Dtype\n"
            "---  ------  --------------  -----\n"
            " 0   x       100 non-null      int64\n"
            " 1   y       100 non-null      int64\n"
            "dtypes: int64(2)\n"
            "memory usage: *\n"
        )
        assert fnmatch.fnmatch(buf.getvalue(), expected)
    elif buf is None:
        assert ret is None
    else:
        raise NotImplementedError(f"Case not covered for kwargs: {kwargs}")


def test_dont_fuse_from_pandas_ops(df, pdf):
    df2 = from_pandas(pdf, npartitions=1)
    df = df.astype("float64")
    result = df.merge(df2)
    dsk = result.optimize().dask
    assert (df2._name, 0) in dsk


def test_column_projection_modify_list(df, pdf):
    cols = ["x"]
    result = df[cols]
    cols.append("bla")
    assert_eq(result, pdf[["x"]])


def test_setitem(pdf, df):
    pdf = pdf.copy()
    pdf["z"] = pdf.x + pdf.y

    df["z"] = df.x + df.y

    assert "z" in df.columns
    assert_eq(df, pdf)


def test_set_index_blockwise_culling(df, pdf):
    result = df.set_index("x").partitions[0]
    assert_eq(result, pdf.set_index("x").head(10))


def test_set_index_with_divisions_already_known():
    ddf = timeseries(start="2021-01-01", end="2021-01-07", freq="1h").reset_index()
    pdf = ddf.compute()
    divisions = pd.date_range(start="2021-01-01", end="2021-01-07", freq="1D")

    ddf2 = ddf.set_index("timestamp", sorted=True, divisions=divisions.tolist())
    assert_eq(ddf2, pdf.set_index("timestamp"))


@xfail_gpu("https://github.com/rapidsai/cudf/issues/10271")
def test_explode():
    with dask.config.set({"dataframe.convert-string": False}):
        pdf = pd.DataFrame({"a": [[1, 2], [3, 4]]})
        df = from_pandas(pdf)
        assert_eq(pdf.explode(column="a"), df.explode(column="a"))
        assert_eq(pdf.a.explode(), df.a.explode())


@xfail_gpu("https://github.com/rapidsai/cudf/issues/10271")
def test_explode_simplify(pdf):
    pdf["z"] = 1
    df = from_pandas(pdf)
    q = df.explode(column="x")["y"]
    result = optimize(q, fuse=False)
    expected = optimize(df[["x", "y"]], fuse=False).explode(column="x")["y"]
    assert result._name == expected._name


def test_meta_divisions_name():
    a = pd.DataFrame({"x": [1, 2, 3, 4], "y": [1.0, 2.0, 3.0, 4.0]})
    df = 2 * from_pandas(a, npartitions=2)
    assert list(df.columns) == list(a.columns)
    assert df.npartitions == 2

    assert np.isscalar(df.x.sum()._meta)
    assert df.x.sum().npartitions == 1

    assert "mul" in df._name
    assert "sum" in df.sum()._name


def test_meta_blockwise():
    a = pd.DataFrame({"x": [1, 2, 3, 4], "y": [1.0, 2.0, 3.0, 4.0]})
    b = pd.DataFrame({"z": [1, 2, 3, 4], "y": [1.0, 2.0, 3.0, 4.0]})

    aa = from_pandas(a, npartitions=2)
    bb = from_pandas(b, npartitions=2)

    cc = 2 * aa - 3 * bb
    assert set(cc.columns) == {"x", "y", "z"}


def test_dask(pdf, df):
    assert (df.x + df.y).npartitions == 10
    z = (df.x + df.y).sum()

    assert assert_eq(z, (pdf.x + pdf.y).sum())


@pytest.mark.parametrize("func", ["cumsum", "cumprod", "cummin", "cummax"])
def test_cumulative_methods(df, pdf, func):
    assert_eq(getattr(df, func)(), getattr(pdf, func)(), check_dtype=False)
    assert_eq(getattr(df.x, func)(), getattr(pdf.x, func)())
    assert_eq(getattr(df, func)(axis=1), getattr(pdf, func)(axis=1))

    q = getattr(df, func)()["x"]
    assert q.simplify()._name == getattr(df.x, func)().simplify()._name

    pdf.loc[slice(None, None, 2), "x"] = np.nan
    df = from_pandas(pdf, npartitions=10)
    assert_eq(
        getattr(df, func)(skipna=False),
        getattr(pdf, func)(skipna=False),
        check_dtype=False,
    )
    assert_eq(getattr(df.x, func)(skipna=False), getattr(pdf.x, func)(skipna=False))

    df = from_pandas(pdf, npartitions=10)
    df["new"] = getattr(df.x, func)()
    pdf["new"] = getattr(pdf.x, func)()

    assert_eq(df, pdf)


def test_bool(df):
    conditions = [df, df["x"], df == df, df["x"] == df["x"]]
    for cond in conditions:
        with pytest.raises(ValueError):
            bool(cond)


def test_map_index():
    df = pd.DataFrame({"x": [1, 2, 3, 4, 5]})
    ddf = from_pandas(df, npartitions=2)
    assert ddf.known_divisions is True

    with pytest.warns(UserWarning):
        cleared = ddf.index.map(lambda x: x * 10)
    assert cleared.known_divisions is False

    with pytest.warns(UserWarning):
        applied = ddf.index.map(lambda x: x * 10, is_monotonic=True)
    assert applied.known_divisions is True
    assert applied.divisions == tuple(x * 10 for x in ddf.divisions)


def test_squeeze():
    df = pd.DataFrame({"x": [1, 3, 6]})
    df2 = pd.DataFrame({"x": [0]})
    s = pd.Series({"test": 0, "b": 100})

    ddf = from_pandas(df, 3)
    ddf2 = from_pandas(df2, 3)
    ds = from_pandas(s, 2)

    assert_eq(df.squeeze(), ddf.squeeze())
    assert_eq(pd.Series([0], name="x"), ddf2.squeeze())
    assert_eq(ds.squeeze(), s.squeeze())

    with pytest.raises(
        NotImplementedError, match=f"{type(ddf)} does not support squeeze along axis 0"
    ):
        ddf.squeeze(axis=0)

    with pytest.raises(ValueError, match=f"No axis {2} for object type {type(ddf)}"):
        ddf.squeeze(axis=2)

    with pytest.raises(ValueError, match=f"No axis test for object type {type(ddf)}"):
        ddf.squeeze(axis="test")


def test_filter_pushdown_reducer_in_predicate():
    pdf = pd.DataFrame(
        {"a": [1, 2, 3, 4, 5, 100], "b": ["a", "b", "b", "a", "b", "c"], "c": 1, "d": 2}
    )
    df = from_pandas(pdf, npartitions=2)
    df = df[df.b.isin(["a", "b"])]
    avg = df["a"].mean()
    result = df[df["a"] > avg]["a"]

    pdf = pdf[pdf.b.isin(["a", "b"])]
    avg = pdf["a"].mean()
    expected = pdf[pdf["a"] > avg]["a"]
    assert_eq(result, expected)
    q = result.simplify()
    assert isinstance(q.expr, Filter)  # Projection was pushed through
    assert isinstance(q.expr.frame, Filter)  # Filters not squashed
    assert isinstance(q.expr.frame.frame.frame, FromPandas)
    assert q.expr.frame.frame.frame.columns == ["a", "b"]


def test_assign_empty_columns(df, pdf):
    df[[]] = df[[]].astype("float64")
    assert list(df.columns) == list(pdf.columns)
    pdf[[]] = pdf[[]].astype("float64")
    assert_eq(df, pdf)


def test_index_divisions():
    df = pd.DataFrame({"x": [1, 2, 3, 4, 5]})
    ddf = from_pandas(df, npartitions=2)

    assert_eq(ddf.index + 1, df.index + 1)
    # dask-expr keeps the range index
    assert_eq(ddf.index + ddf.index, df.index + df.index, check_dtype=False)
    assert_eq(10 * ddf.index, 10 * df.index)
    assert_eq(-ddf.index, -df.index)


@xfail_gpu("nbytes not supported by cudf")
def test_nbytes(pdf, df):
    with pytest.raises(NotImplementedError, match="nbytes is not implemented"):
        df.nbytes
    assert_eq(df.x.nbytes, pdf.x.nbytes)


def test_pop(pdf, df):
    s = df.pop("y")
    assert s.name == "y"
    assert df.columns == ["x"]
    assert_eq(df, pdf[["x"]])


def test_dot():
    import dask.array as da

    s1 = pd.Series([1, 2, 3, 4])
    s2 = pd.Series([4, 5, 6, 6])
    df = pd.DataFrame({"one": s1, "two": s2})

    dask_s1 = from_pandas(s1, npartitions=1)
    dask_df = from_pandas(df, npartitions=1)
    dask_s2 = from_pandas(s2, npartitions=1)

    assert_eq(s1.dot(s2), dask_s1.dot(dask_s2))
    assert_eq(s1.dot(df), dask_s1.dot(dask_df))

    # With partitions
    partitioned_s1 = from_pandas(s1, npartitions=2)
    partitioned_df = from_pandas(df, npartitions=2)
    partitioned_s2 = from_pandas(s2, npartitions=2)

    assert_eq(s1.dot(s2), partitioned_s1.dot(partitioned_s2))
    assert_eq(s1.dot(df), partitioned_s1.dot(partitioned_df))

    # Test passing meta kwarg
    res = dask_s1.dot(dask_df, meta=pd.Series([1], name="test_series")).compute()
    assert res.name == "test_series"

    # Test validation of second operand
    with pytest.raises(TypeError):
        dask_s1.dot(da.array([1, 2, 3, 4]))


def test_pipe():
    df = pd.DataFrame({"x": range(50), "y": range(50, 100)})
    ddf = from_pandas(df, npartitions=4)

    def f(x, y, z=0):
        return x + y + z

    assert_eq(ddf.pipe(f, 1, z=2), f(ddf, 1, z=2))
    assert_eq(ddf.x.pipe(f, 1, z=2), f(ddf.x, 1, z=2))


def test_mode():
    pdf = pd.DataFrame({"x": [1, 2, 3, 1, 2]})
    df = from_pandas(pdf, npartitions=3)

    assert_eq(df.x.mode(), pdf.x.mode(), check_names=False)


def test_value_counts(df, pdf):
    with pytest.raises(
        AttributeError, match="'DataFrame' object has no attribute 'value_counts'"
    ):
        df.value_counts()
    assert_eq(df.x.value_counts(), pdf.x.value_counts().astype("int64"))


def test_dropna(pdf):
    pdf.loc[0, "y"] = np.nan
    df = from_pandas(pdf)
    assert_eq(df.dropna(), pdf.dropna())
    assert_eq(df.dropna(how="all"), pdf.dropna(how="all"))
    assert_eq(df.y.dropna(), pdf.y.dropna())


def test_value_counts_with_dropna():
    pdf = pd.DataFrame({"x": [1, 2, 1, 3, np.nan, 1, 4]})
    df = from_pandas(pdf, npartitions=3)
    result = df.x.value_counts(dropna=False)
    expected = pdf.x.value_counts(dropna=False)
    assert_eq(result, expected)


def test_fillna():
    pdf = pd.DataFrame({"x": [1, 2, None, None, 5, 6]})
    df = from_pandas(pdf, npartitions=2)
    actual = df.fillna(value=100)
    expected = pdf.fillna(value=100)
    assert_eq(actual, expected)


@pytest.mark.parametrize("limit", (None, 1, 2))
@pytest.mark.parametrize("how", ("ffill", "bfill"))
@pytest.mark.parametrize("axis", ("index", "columns", 0, 1))
def test_ffill_and_bfill(limit, axis, how):
    if limit is None:
        pytest.xfail("Need to determine partition size for Fill.before <= frame size")
    if axis in (1, "columns"):
        pytest.xfail("bfill/ffill not implemented for axis 1")
    pdf = pd.DataFrame({"x": [1, 2, None, None, 5, 6]})
    df = from_pandas(pdf, npartitions=2)
    actual = getattr(df, how)(axis=axis, limit=limit)
    expected = getattr(pdf, how)(axis=axis, limit=limit)
    assert_eq(actual, expected)


def test_reset_index_projections(pdf):
    pdf = pdf.set_index("x").y
    df = from_pandas(pdf, npartitions=10)
    assert_eq(df.reset_index().y, pdf.reset_index().y, check_index=False)
    assert_eq(df.reset_index().x, pdf.reset_index().x, check_index=False)
    q = df.reset_index()
    q = q + q.x.sum()
    expected = pdf.reset_index()
    expected = expected + expected.x.sum()
    assert_eq(q, expected, check_index=False)

    pdf = pdf.to_frame()
    df = from_pandas(pdf, npartitions=10)
    assert_eq(df.y.reset_index()[["y"]], pdf.y.reset_index()[["y"]], check_index=False)


def test_series_map_meta():
    ser = pd.Series(
        ["".join(np.random.choice(["a", "b", "c"], size=3)) for x in range(100)]
    )

    mapper = pd.Series(np.random.randint(50, size=len(ser)))
    expected = ser.map(mapper)
    dask_base = from_pandas(ser, npartitions=5)
    dask_map = from_pandas(mapper, npartitions=5)
    with pytest.warns(UserWarning):
        result = dask_base.map(dask_map)
    assert_eq(expected, result)


@pytest.mark.parametrize("periods", (1, 2))
@pytest.mark.parametrize("freq", (None, "1h", timedelta(hours=1)))
@pytest.mark.parametrize("axis", ("index", 0, "columns", 1))
def test_shift(pdf, df, periods, freq, axis):
    if freq and axis in ("columns", 1):
        pytest.skip(reason="Neither dask or pandas supports freq w/ axis 1 shift")

    if freq is not None:
        pdf["time"] = pd.date_range("2000-01-01", "2000-01-02", periods=len(pdf))
        pdf = pdf.set_index("time", drop=True)
        df = from_pandas(pdf, npartitions=df.npartitions)

    actual = df.shift(periods=periods, axis=axis, freq=freq)
    expected = pdf.shift(periods=periods, axis=axis, freq=freq)
    assert_eq(actual, expected)


def test_memory_usage(pdf):
    # Results are not equal with RangeIndex because pandas has one RangeIndex while
    # we have one RangeIndex per partition
    pdf.index = np.arange(len(pdf))
    df = from_pandas(pdf)
    assert_eq(df.memory_usage(), pdf.memory_usage())
    assert_eq(df.memory_usage(index=False), pdf.memory_usage(index=False))
    assert_eq(df.x.memory_usage(), pdf.x.memory_usage())
    assert_eq(df.x.memory_usage(index=False), pdf.x.memory_usage(index=False))
    assert_eq(df.index.memory_usage(), pdf.index.memory_usage())
    with pytest.raises(TypeError, match="got an unexpected keyword"):
        df.index.memory_usage(index=True)


@pytest.mark.parametrize("func", [M.nlargest, M.nsmallest])
def test_nlargest_nsmallest(df, pdf, func):
    assert_eq(func(df, n=5, columns="x"), func(pdf, n=5, columns="x"))
    assert_eq(func(df.x, n=5), func(pdf.x, n=5))
    with pytest.raises(TypeError, match="got an unexpected keyword argument"):
        func(df.x, n=5, columns="foo")


@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.x > 10,
        lambda df: df.x.gt(10),
        lambda df: df.x + 20 > df.y,
        lambda df: 10 < df.x,
        lambda df: df.x.lt(10),
        lambda df: 10 <= df.x,
        lambda df: df.x.le(10),
        lambda df: 10 == df.x,
        lambda df: df.x.eq(10),
        lambda df: df.x < df.y,
        lambda df: df.lt(df),
        lambda df: df.x.lt(df.y),
        lambda df: df.x > df.y,
        lambda df: df.gt(df),
        lambda df: df.x.gt(df.y),
        lambda df: df.x == df.y,
        lambda df: df.eq(df),
        lambda df: df.x.eq(df.y),
        lambda df: df.x != df.y,
        lambda df: df.ne(df),
        lambda df: df.x.ne(df.y),
    ],
)
def test_conditionals(func, pdf, df):
    assert_eq(func(pdf), func(df), check_names=False)


@pytest.mark.parametrize("axis", ("index", 0, "columns", 1, None))
@pytest.mark.parametrize("periods", (1, 2, None))
def test_diff(pdf, df, axis, periods):
    kwargs = {k: v for k, v in (("periods", periods), ("axis", axis)) if v}

    actual = df.diff(**kwargs)
    expected = pdf.diff(**kwargs)
    assert_eq(expected, actual)

    # Check projections
    expected = df[["x"]].diff(**kwargs)
    actual = df.diff(**kwargs)[["x"]]

    # no optimization on axis 1
    if axis in ("columns", 1):
        assert actual._name == actual.simplify()._name
    else:
        assert actual.simplify()._name == expected.simplify()._name


@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.x & df.y,
        lambda df: df.x.__rand__(df.y),
        lambda df: df.x | df.y,
        lambda df: df.x.__ror__(df.y),
        lambda df: df.x ^ df.y,
        lambda df: df.x.__rxor__(df.y),
    ],
)
def test_boolean_operators(func):
    pdf = pd.DataFrame(
        {"x": [True, False, True, False], "y": [True, False, False, False]}
    )
    df = from_pandas(pdf)
    assert_eq(func(pdf), func(df))


@pytest.mark.parametrize("axis", ("columns", 1, "index", 0))
@pytest.mark.parametrize("level", (None, 0, "x"))
@pytest.mark.parametrize("fill_value", (None, 1))
@pytest.mark.parametrize(
    "op",
    (
        "add",
        "sub",
        "mul",
        "div",
        "divide",
        "truediv",
        "floordiv",
        "mod",
        "pow",
        "radd",
        "rsub",
        "rmul",
        "rdiv",
        "rtruediv",
        "rfloordiv",
        "rmod",
        "rpow",
    ),
)
@pytest.mark.parametrize("series", (True, False))
@pytest.mark.parametrize("other", ("series", "dataframe", 1))
def test_method_operators(pdf, df, axis, level, fill_value, op, series, other):
    kwargs = {
        k: v
        for k, v in (("axis", axis), ("level", level), ("fill_value", fill_value))
        if v is not None
    }

    if level is not None:
        with pytest.raises(NotImplementedError, match="level must be None"):
            getattr(df, op)(other=df, **kwargs)
        return

    if other == "series":
        pother = pdf.x
        other = df.x
    elif other == "dataframe":
        pother = pdf
        other = df
    else:
        pother = other

    if isinstance(other, Series) and axis in (1, "columns"):
        with pytest.raises(ValueError, match=f"Unable to {op} dd.Series with axis=1"):
            getattr(df, op)(other=other, **kwargs)

    elif isinstance(other, Series) and axis in (0, "index") and fill_value:
        msg = f"fill_value {fill_value} not supported"
        with pytest.raises(NotImplementedError, match=msg):
            getattr(df, op)(other=other, **kwargs)

    else:
        expected = getattr(pdf, op)(other=pother, **kwargs)
        actual = getattr(df, op)(other=other, **kwargs)
        assert_eq(expected, actual)


@pytest.mark.parametrize(
    "func",
    [
        lambda df: ~df,
        lambda df: ~df.x,
        lambda df: -df.z,
        lambda df: +df.z,
        lambda df: -df,
        lambda df: +df,
    ],
)
def test_unary_operators(func):
    pdf = pd.DataFrame(
        {"x": [True, False, True, False], "y": [True, False, False, False], "z": 1}
    )
    df = from_pandas(pdf)
    assert_eq(func(pdf), func(df))


@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.x + df.y,
        lambda df: 2 * df.x,
        lambda df: df.x * df.y,
        lambda df: df.x - df.y,
        lambda df: df.x**2,
    ],
)
def test_binary_operator(pdf, df, func):
    assert_eq(func(pdf), func(df))


@pytest.mark.parametrize(
    "func",
    [
        lambda df: df[(df.x > 10) | (df.x < 5)],
        lambda df: df[(df.x > 7) & (df.x < 10)],
    ],
)
def test_and_or(func, pdf, df):
    assert_eq(func(pdf), func(df), check_names=False)


@xfail_gpu("period_range not supported by cudf")
@pytest.mark.parametrize("how", ["start", "end"])
def test_to_timestamp(pdf, how):
    pdf.index = pd.period_range("2019-12-31", freq="D", periods=len(pdf))
    df = from_pandas(pdf)
    assert_eq(df.to_timestamp(how=how), pdf.to_timestamp(how=how))
    assert_eq(df.x.to_timestamp(how=how), pdf.x.to_timestamp(how=how))


@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.astype(int),
        lambda df: df.clip(lower=10, upper=50),
        lambda df: df.x.clip(lower=10, upper=50),
        lambda df: df.clip(lower=3, upper=7, axis=1),
        lambda df: df.x.between(left=10, right=50),
        lambda df: df[df.x > 5],
        lambda df: df.assign(a=df.x + df.y, b=df.x - df.y),
        lambda df: df.assign(a=df.x + df.y, b=lambda x: x.a + 1),
        lambda df: df.replace(to_replace=1, value=1000),
        lambda df: df.x.replace(to_replace=1, value=1000),
        lambda df: df.isna(),
        lambda df: isna(df),
        lambda df: isna(df.x),
        lambda df: df.x.isna(),
        lambda df: df.isnull(),
        lambda df: df.x.isnull(),
        lambda df: df.mask(df.x == 10, 42),
        lambda df: df.mask(df.x == 10),
        lambda df: df.mask(lambda df: df.x % 2 == 0, 42),
        lambda df: df.mask(df.x == 10, df + 2),
        lambda df: df.mask(df.x == 10, lambda df: df + 2),
        lambda df: df.x.mask(df.x == 10, 42),
        lambda df: df.abs(),
        lambda df: df.x.abs(),
        lambda df: df.where(df.x == 10, 42),
        lambda df: df.where(df.x == 10),
        lambda df: df.where(lambda df: df.x % 2 == 0, 42),
        lambda df: df.where(df.x == 10, df + 2),
        lambda df: df.where(df.x == 10, lambda df: df + 2),
        lambda df: df.x.where(df.x == 10, 42),
        lambda df: df.rename(columns={"x": "xx"}),
        lambda df: df.rename(columns={"x": "xx"}).xx,
        lambda df: df.rename(columns={"x": "xx"})[["xx"]],
        lambda df: df.x.rename(index="hello"),
        lambda df: df.x.rename(index=df.x),
        lambda df: df.x.rename(index=("hello",)),
        lambda df: df.x.to_frame(),
        lambda df: df.drop(columns="x"),
        lambda df: df.drop(axis=1, labels=["x"]),
        lambda df: df.x.index.to_series(),
        lambda df: df.x.index.to_frame(),
        lambda df: df.x.index.to_series(name="abc"),
        lambda df: df.x.index.to_frame(name="abc"),
        lambda df: df.eval("z=x+y"),
        lambda df: df.select_dtypes(include="integer"),
        lambda df: df.add_prefix(prefix="2_"),
        lambda df: df.add_suffix(suffix="_2"),
        lambda df: df.query("x > 10"),
    ],
)
def test_blockwise(func, pdf, df):
    assert_eq(func(pdf), func(df))


def test_add_prefix():
    df = pd.DataFrame({"x": [1, 2, 3, 4, 5], "y": [4, 5, 6, 7, 8]})
    ddf = from_pandas(df, npartitions=2)
    assert_eq(ddf.add_prefix("abc"), df.add_prefix("abc"))
    assert_eq(ddf.x.add_prefix("abc"), df.x.add_prefix("abc"))


def test_add_suffix():
    df = pd.DataFrame({"x": [1, 2, 3, 4, 5], "y": [4, 5, 6, 7, 8]})
    ddf = from_pandas(df, npartitions=2)
    assert_eq(ddf.add_suffix("abc"), df.add_suffix("abc"))
    assert_eq(ddf.x.add_suffix("abc"), df.x.add_suffix("abc"))


def test_select_dtypes_projection(df):
    result = df.select_dtypes(np.number)
    assert isinstance(result.expr.operand("columns"), list)


def test_rename(pdf, df):
    q = df.x.rename({1: 2})
    assert q.divisions[0] is None
    assert_eq(q, pdf.x.rename({1: 2}))

    q = df.x.rename(lambda x: x)
    assert q.divisions[0] is None
    assert_eq(q, pdf.x.rename(lambda x: x))

    q = df.x.rename({1: 2}, sorted_index=True)
    assert q.divisions[0] is not None
    assert_eq(q, pdf.x.rename({1: 2}))

    q = df.x.rename(lambda x: x, sorted_index=True)
    assert q.divisions[0] is not None
    assert_eq(q, pdf.x.rename(lambda x: x))

    with pytest.raises(ValueError, match="non-monotonic"):
        df.x.rename({0: 200}, sorted_index=True).divisions


def test_mask_where(df, pdf):
    cond = df.x == 10
    pcond = pdf.x == 10
    df = df.repartition(list(df.divisions)[::2] + [99])
    assert_eq(df.where(cond, 42), pdf.where(pcond, 42))
    assert_eq(df.mask(cond, 42), pdf.mask(pcond, 42))


def test_isna(pdf):
    pdf.iloc[list(range(0, len(pdf), 2)), 0] = np.nan
    df = from_pandas(pdf, npartitions=10)
    assert_eq(isna(df.x), pd.isna(pdf.x))
    assert_eq(isna(df), pd.isna(pdf))
    assert_eq(isna(pdf.x), pd.isna(pdf.x))


def test_clear_divisions(df):
    result = df.clear_divisions()
    assert not result.known_divisions
    assert_eq(df, result, check_divisions=False)


def test_abs_errors():
    df = pd.DataFrame(
        {
            "A": [1, -2, 3, -4, 5],
            "C": ["a", "b", "c", "d", "e"],
        }
    )
    ddf = from_pandas(df, npartitions=2)
    pytest.raises((TypeError, NotImplementedError, ValueError), lambda: ddf.C.abs())
    pytest.raises((TypeError, NotImplementedError), lambda: ddf.abs())


def test_to_datetime():
    pdf = pd.DataFrame({"year": [2015, 2016], "month": [2, 3], "day": [4, 5]})
    df = from_pandas(pdf, npartitions=2)
    expected = pd.to_datetime(pdf)
    result = to_datetime(df)
    assert_eq(result, expected)

    ps = pd.Series(["2018-10-26 12:00:00", "2018-10-26 13:00:15"])
    ds = from_pandas(ps, npartitions=2)
    expected = pd.to_datetime(ps)
    result = to_datetime(ds)
    assert_eq(result, expected)

    result = to_datetime(ps)
    assert_eq(result, expected)

    expected = pd.to_datetime(ps.index)
    result = to_datetime(ds.index)
    assert_eq(result, expected, check_divisions=False)

    with pytest.raises(NotImplementedError, match="non-index-able arguments"):
        to_datetime(1490195805)


def test_to_numeric(pdf, df):
    import dask.array as da

    pdf.x = pdf.x.astype("str")
    expected = pd.to_numeric(pdf.x)
    df.x = df.x.astype("str")
    result = to_numeric(df.x)
    assert_eq(result, expected)

    result = to_numeric("1.0").compute()
    assert result == 1.0

    arr = df.x.to_dask_array()
    expected = pd.to_numeric(pdf.x.to_numpy())
    result = to_numeric(arr)
    da.assert_eq(result, expected)


def test_to_timedelta(pdf, df):
    expected = pd.to_timedelta(pdf.x)
    result = to_timedelta(df.x)
    assert_eq(result, expected)

    with pytest.raises(TypeError, match="arg must be a Series"):
        to_timedelta("1.0")


def test_drop_not_implemented(pdf, df):
    msg = "Drop currently only works for axis=1 or when columns is not None"
    with pytest.raises(NotImplementedError, match=msg):
        df.drop(axis=0, labels=[0])


@xfail_gpu("func not supported by cudf")
@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.combine_first(df),
        lambda df: df.x.combine_first(df.y),
    ],
)
def test_blockwise_pandas_only(func, pdf, df):
    assert_eq(func(pdf), func(df))


@xfail_gpu("func not supported by cudf")
@pytest.mark.parametrize(
    "func",
    [
        lambda df: df.apply(lambda row, x, y=10: row * x + y, x=2, axis=1),
        lambda df: df.index.map(lambda x: x + 1),
        pytest.param(
            lambda df: df.map(lambda x: x + 1),
            marks=pytest.mark.skipif(
                not PANDAS_GE_210, reason="Only available from 2.1"
            ),
        ),
        lambda df: df.x.map(lambda x: x + 1),
    ],
)
def test_blockwise_pandas_only_warning(func, pdf, df):
    with pytest.warns(UserWarning):
        assert_eq(func(pdf), func(df))


def test_map_meta(pdf, df):
    expected = pdf.x.map(lambda x: x + 1)
    result = df.x.map(lambda x: x + 1, meta=expected.iloc[:0])
    assert_eq(result, expected)

    result = df.x.map(df.x + 1, meta=expected.iloc[:0])
    assert_eq(result, expected)

    result = df.x.map(df.x + 1, meta=("x", "int64"))
    assert_eq(result, expected)

    result = df.x.map((df.x + 1).compute(), meta=("x", "int64"))
    assert_eq(result, expected)

    pdf.index.name = "a"
    df = from_pandas(pdf, npartitions=10)
    result = df.x.map(lambda x: x + 1, meta=("x", "int64"))
    assert_eq(result, expected)


def test_simplify_add_suffix_add_prefix(df, pdf):
    result = df.add_prefix("2_")["2_x"].simplify()
    expected = df[["x"]].simplify().add_prefix("2_")["2_x"]
    assert result._name == expected._name
    assert_eq(result, pdf.add_prefix("2_")["2_x"])

    result = df.add_suffix("_2")["x_2"].simplify()
    expected = df[["x"]].simplify().add_suffix("_2")["x_2"]
    assert result._name == expected._name
    assert_eq(result, pdf.add_suffix("_2")["x_2"])


@xfail_gpu("rename_axis not supported by cudf")
def test_rename_axis(pdf):
    pdf.index.name = "a"
    pdf.columns.name = "b"
    df = from_pandas(pdf, npartitions=10)
    assert_eq(df.rename_axis(index="dummy"), pdf.rename_axis(index="dummy"))
    assert_eq(df.rename_axis(columns="dummy"), pdf.rename_axis(columns="dummy"))
    assert_eq(df.x.rename_axis(index="dummy"), pdf.x.rename_axis(index="dummy"))


def test_series_name(pdf, df):
    pser = pdf.x
    ser = df.x
    assert ser.name == pser.name
    ser.name = "y"
    assert ser.name == "y"


def test_isin(df, pdf):
    values = [1, 2]
    assert_eq(pdf.isin(values), df.isin(values))
    assert_eq(pdf.x.isin(values), df.x.isin(values))


def test_isin_repr(df):
    result = df.isin([1, 2])
    # This was raising previously
    result = result.__repr__()
    assert "Expr=Isin(frame=df, values=" in result


def test_round(pdf):
    pdf += 0.5555
    df = from_pandas(pdf)
    assert_eq(df.round(decimals=1), pdf.round(decimals=1))
    assert_eq(df.x.round(decimals=1), pdf.x.round(decimals=1))


def test_repr(df):
    assert "+ 1" in str(df + 1)
    assert "+ 1" in repr(df + 1)

    s = (df["x"] + 1).sum(skipna=False).expr
    assert '["x"]' in str(s) or "['x']" in str(s)
    assert "+ 1" in str(s)
    assert "sum(skipna=False)" in str(s)


@xfail_gpu("combine_first not supported by cudf")
def test_combine_first_simplify(pdf):
    df = from_pandas(pdf)
    pdf2 = pdf.rename(columns={"y": "z"})
    df2 = from_pandas(pdf2)

    q = df.combine_first(df2)[["z", "y"]]
    result = q.simplify()
    expected = df[["y"]].simplify().combine_first(df2[["z"]].simplify())[["z", "y"]]
    assert result._name == expected._name
    assert_eq(result, pdf.combine_first(pdf2)[["z", "y"]])


def test_rename_traverse_filter(df):
    result = df.rename(columns={"x": "xx"})[["xx"]].simplify()
    expected = df[["x"]].simplify().rename(columns={"x": "xx"})
    assert str(result) == str(expected)


def test_columns_traverse_filters(pdf):
    pdf = pdf.copy()
    pdf["z"] = pdf["x"]
    df = from_pandas(pdf, npartitions=10)
    result = df[df.x > 5].y.optimize(fuse=False)
    df_opt = df[["x", "y"]].simplify()
    expected = df_opt.y[df_opt.x > 5]

    assert result._name == expected._name


def test_clip_traverse_filters(df):
    result = df.clip(lower=10).y.simplify()
    expected = df.y.simplify().clip(lower=10)

    assert result._name == expected._name

    result = df.clip(lower=10)[["x", "y"]].simplify()
    expected = df.clip(lower=10)

    assert result._name == expected._name

    arg = df.clip(lower=10)[["x"]]
    result = arg.simplify()
    expected = df[["x"]].simplify().clip(lower=10)

    assert result._name == expected._name


@pytest.mark.parametrize("projection", ["zz", ["zz"], ["zz", "x"], "zz"])
@pytest.mark.parametrize("subset", ["x", ["x"]])
def test_drop_duplicates_subset_simplify(pdf, subset, projection):
    pdf["zz"] = 1
    df = from_pandas(pdf)
    result = df.drop_duplicates(subset=subset)[projection].simplify()
    expected = df[["x", "zz"]].simplify().drop_duplicates(subset=subset)[projection]

    assert str(result) == str(expected)


def test_rename_columns():
    # Multi-index columns
    pdf = pd.DataFrame({("A", "0"): [1, 2, 2, 3], ("B", 1): [1, 2, 3, 4]})
    df = from_pandas(pdf, npartitions=2)

    df.columns = ["x", "y"]
    pdf.columns = ["x", "y"]
    pd.testing.assert_index_equal(df.columns, pd.Index(["x", "y"]))
    pd.testing.assert_index_equal(df._meta.columns, pd.Index(["x", "y"]))


def test_columns_named_divisions_and_meta():
    df = pd.DataFrame(
        {"_meta": [1, 2, 3, 4], "divisions": ["a", "b", "c", "d"]},
        index=[0, 1, 3, 5],
    )
    ddf = from_pandas(df, npartitions=2)

    assert ddf.divisions == (0, 3, 5)
    assert_eq(ddf["divisions"], df.divisions)
    assert all(ddf._meta.columns == ["_meta", "divisions"])
    assert_eq(ddf["_meta"], df._meta)


def test_broadcast(pdf, df):
    assert_eq(
        df + df.sum(),
        pdf + pdf.sum(),
    )
    assert_eq(
        df.x + df.x.sum(),
        pdf.x + pdf.x.sum(),
    )


def test_persist(pdf, df):
    a = df + 2
    a *= 2
    b = a.persist()

    assert_eq(a, b)
    assert len(a.__dask_graph__()) > len(b.__dask_graph__())

    assert len(b.__dask_graph__()) == 2 * b.npartitions

    assert_eq(b.y.sum(), ((pdf + 2) * 2).y.sum())


def test_index(pdf, df):
    assert_eq(df.index, pdf.index)
    assert_eq(df.x.index, pdf.x.index)
    df.index = df.index.astype("float64")
    pdf.index = pdf.index.astype("float64")
    assert_eq(df, pdf)
    with pytest.raises(AssertionError, match="aligned"):
        df.index = df.repartition(npartitions=2).index


@pytest.mark.parametrize("drop", [True, False])
def test_reset_index(pdf, df, drop):
    assert_eq(df.reset_index(drop=drop), pdf.reset_index(drop=drop), check_index=False)
    assert_eq(
        df.x.reset_index(drop=drop), pdf.x.reset_index(drop=drop), check_index=False
    )


def test_head(pdf, df):
    assert_eq(df.head(compute=False), pdf.head())
    assert_eq(df.head(compute=False, n=7), pdf.head(n=7))

    assert df.head(compute=False).npartitions == 1
    assert_eq(df.index.head(compute=False, n=7), pdf.index[0:7])

    assert_eq(df.head(15, npartitions=2), pdf.head(15))
    with pytest.warns(UserWarning, match="Insufficient elements"):
        assert_eq(df.head(22, npartitions=2), pdf.head(20))

    assert_eq(df.head(100, npartitions=-1), pdf.head(100))
    assert_eq(df.head(5, npartitions=-1), pdf.head(5))


def test_head_down(df):
    result = (df.x + df.y + 1).head(compute=False)
    optimized = result.simplify()

    assert_eq(result, optimized)

    assert not isinstance(optimized.expr, expr.Head)


@pytest.mark.skipif(not PANDAS_GE_220, reason="not implemented")
def test_case_when(pdf, df):
    result = df.x.case_when([(df.x.eq(1), 1), (df.y == 10, 2.5)])
    expected = pdf.x.case_when([(pdf.x.eq(1), 1), (pdf.y == 10, 2.5)])
    assert_eq(result, expected)


def test_head_head(df):
    a = df.head(compute=False).head(compute=False)
    b = df.head(compute=False)

    assert a.optimize()._name == b.optimize()._name


def test_head_npartitions(df):
    full = df.compute()
    length = len(full)

    assert_eq(df.head(5, npartitions=2), full.head(5))
    assert_eq(df.head(5, npartitions=2, compute=False), full.head(5))
    assert_eq(df.head(5, npartitions=-1), full.head(5))
    assert_eq(df.head(7, npartitions=-1), full.head(7))
    assert_eq(df.head(2, npartitions=-1), full.head(2))
    with pytest.raises(ValueError):
        df.head(2, npartitions=length + 1)


def test_head_tail_repartition(df):
    q = df.head(compute=False).repartition(npartitions=1).optimize()
    expected = df.head(compute=False).optimize()
    assert q._name == expected._name

    q = df.tail(compute=False).repartition(npartitions=1).optimize()
    expected = df.tail(compute=False).optimize()
    assert q._name == expected._name


def test_tail(pdf, df):
    assert_eq(df.tail(compute=False), pdf.tail())
    assert_eq(df.tail(compute=False, n=7), pdf.tail(n=7))

    assert df.tail(compute=False).npartitions == 1
    assert_eq(df.index.tail(compute=False, n=7), pdf.index[-7:])


def test_tail_down(df):
    result = (df.x + df.y + 1).tail(compute=False)
    optimized = optimize(result)

    assert_eq(result, optimized)

    assert not isinstance(optimized.expr, expr.Tail)


def test_tail_tail(df):
    a = df.tail(compute=False).tail(compute=False)
    b = df.tail(compute=False)

    assert a.optimize()._name == b.optimize()._name


def test_tail_repartition(df):
    a = df.repartition(npartitions=10).tail()
    b = df.tail()
    assert_eq(a, b)


def test_projection_stacking(df):
    result = df[["x", "y"]]["x"]
    optimized = result.simplify()
    expected = df["x"].simplify()

    assert optimized._name == expected._name


def test_projection_stacking_coercion(pdf):
    df = from_pandas(pdf)
    assert_eq(df.x[0], pdf.x[0], check_divisions=False)
    assert_eq(df.x[[0]], pdf.x[[0]], check_divisions=False)


def test_projection_pushdown_dim_0(pdf, df):
    result = (df[["x"]] + df["x"].sum(skipna=False))["x"]
    expected = (pdf[["x"]] + pdf["x"].sum(skipna=False))["x"]
    assert_eq(result, expected)
    assert_eq(result.optimize(), expected)


def test_remove_unnecessary_projections(df):
    result = (df + 1)[df.columns]
    optimized = result.simplify()
    expected = df + 1

    assert optimized._name == expected._name

    result = (df[["x"]] + 1)[["x"]]
    optimized = result.simplify()
    expected = df[["x"]].simplify() + 1

    assert optimized._name == expected._name


def test_substitute():
    pdf = pd.DataFrame(
        {
            "a": range(100),
            "b": range(100),
            "c": range(100),
        }
    )
    df = from_pandas(pdf, npartitions=3)
    df = df.expr

    result = (df + 1).substitute(1, 2)
    expected = df + 2
    assert result._name == expected._name

    result = df["a"].substitute(df["a"], df["b"])
    expected = df["b"]
    assert result._name == expected._name

    result = (df["a"] - df["b"]).substitute(df["b"], df["c"])
    expected = df["a"] - df["c"]
    assert result._name == expected._name

    result = df["a"].substitute(3, 4)
    expected = from_pandas(pdf, npartitions=4).a
    assert result._name == expected._name

    result = (df["a"].sum() + 5).substitute(df["a"], df["b"]).substitute(5, 6)
    expected = df["b"].sum() + 6
    assert result._name == expected._name


def test_substitute_parameters(df):
    pdf = pd.DataFrame(
        {
            "a": range(100),
            "b": range(100),
            "c": range(100),
            "index": range(100, 0, -1),
        }
    )
    df = from_pandas(pdf, npartitions=3, sort=True)

    result = df.substitute_parameters({"sort": False})
    assert result._name != df._name
    assert result._name == from_pandas(pdf, npartitions=3, sort=False)._name

    result = df.substitute_parameters({"npartitions": 2, "sort": False})
    assert result._name != df._name
    assert result._name == from_pandas(pdf, npartitions=2, sort=False)._name

    df2 = df[["a", "b"]]
    result = df2.substitute_parameters({"columns": "c"})
    assert result._name != df2._name
    assert result._name == df["c"]._name


def test_ffill_bfill_all_nan_partition():
    ser = pd.Series([1, np.nan, np.nan, np.nan, np.nan, np.nan, np.nan, np.nan, 2])
    dser = from_pandas(ser, npartitions=3)
    with pytest.raises(ValueError, match="All NaN partition"):
        dser.bfill(limit=None).compute()
    with pytest.raises(ValueError, match="All NaN partition"):
        dser.ffill(limit=None).compute()

    assert_eq(dser.bfill(limit=2), ser.bfill(limit=2))
    assert_eq(dser.ffill(limit=2), ser.ffill(limit=2))

    ser = pd.Series([np.nan, np.nan, np.nan, 2, 3, np.nan])
    dser = from_pandas(ser, npartitions=2)
    assert_eq(dser.ffill(), ser.ffill())

    ser = pd.Series([2, np.nan, 3, np.nan, np.nan, np.nan])
    dser = from_pandas(ser, npartitions=2)
    assert_eq(dser.bfill(), ser.bfill())


def test_copy(df):
    original = df.copy()
    columns = tuple(original.columns)

    df["z"] = df.x + df.y

    assert tuple(original.columns) == columns
    assert "z" not in original.columns


def test_partitions(pdf, df):
    assert_eq(df.partitions[0], pdf.iloc[:10])
    assert_eq(df.partitions[1], pdf.iloc[10:20])
    assert_eq(df.partitions[1:3], pdf.iloc[10:30])
    assert_eq(df.partitions[[3, 4]], pdf.iloc[30:50])
    assert_eq(df.partitions[-1], pdf.iloc[90:])

    out = (df + 1).partitions[0].simplify()
    assert isinstance(out.expr, expr.Add)
    assert out.expr.left._partitions == [0]

    # Check culling
    out = optimize(df.partitions[1])
    assert len(out.dask) == 1
    assert_eq(out, pdf.iloc[10:20])


def test_get_partition(pdf, df):
    assert_eq(df.get_partition(0), pdf.iloc[:10])
    assert_eq(df.get_partition(1), pdf.iloc[10:20])
    assert_eq(df.x.get_partition(0), pdf.x.iloc[:10])


def test_column_getattr(df):
    df = df.expr
    assert df.x._name == df["x"]._name

    with pytest.raises(AttributeError):
        df.foo


def test_serialization(pdf, df):
    before = pickle.dumps(df)

    assert len(before) < 200 + len(pickle.dumps(pdf))

    part = df.partitions[0].compute()
    assert (
        len(pickle.dumps(df.__dask_graph__()))
        < 1000 + len(pickle.dumps(part)) * df.npartitions
    )

    after = pickle.dumps(df)

    assert before == after  # caching doesn't affect serialization

    assert pickle.loads(before)._name == pickle.loads(after)._name
    assert_eq(pickle.loads(before), pickle.loads(after))


@xfail_gpu("Cannot apply lambda function in cudf")
def test_size_optimized(df):
    with pytest.warns(UserWarning, match="metadata"):
        expr = (df.x + 1).apply(lambda x: x).size
    out = optimize(expr)
    expected = optimize(df.x.size)
    assert out._name == expected._name

    with pytest.warns(UserWarning, match="metadata"):
        expr = (df + 1).apply(lambda x: x, axis=1).size
    out = optimize(expr)
    expected = optimize(df.size)
    assert out._name == expected._name


def test_series_iter(df, pdf):
    for a, b in zip(df["x"], pdf["x"]):
        assert a == b


def test_dataframe_iterrows(df, pdf):
    for a, b in zip(df.iterrows(), pdf.iterrows()):
        pd.testing.assert_series_equal(a[1], b[1])


def test_dataframe_itertuples(df, pdf):
    for a, b in zip(df.itertuples(), pdf.itertuples()):
        assert a == b


def test_array_assignment(df, pdf):
    orig = df.copy()

    arr = np.array(np.random.normal(size=100))
    darr = da.from_array(arr, chunks=10)

    pdf["z"] = arr
    df["z"] = darr
    assert_eq(pdf, df)
    assert "z" not in orig.columns


def test_columns_assignment():
    df = pd.DataFrame({"x": [1, 2, 3, 4]})
    ddf = from_pandas(df, npartitions=2)

    df2 = df.assign(y=df.x + 1, z=df.x - 1)
    df[["a", "b"]] = df2[["y", "z"]]

    ddf2 = ddf.assign(y=ddf.x + 1, z=ddf.x - 1)
    ddf[["a", "b"]] = ddf2[["y", "z"]]

    assert_eq(df, ddf)


def test_parent_mixed_column_assignment():
    pdf = pd.DataFrame(list(range(20)))
    df = from_pandas(pdf, npartitions=4)
    df["a"] = 0
    df["a"] = df["a"].map_partitions(
        lambda x: pd.Series(
            np.full(len(x), 1, dtype="int"),
            index=x.index,
        )
    )
    pdf["a"] = pd.Series(np.full(len(pdf), 1, dtype="int"))
    assert_eq(df, pdf)


def test_drop_duplicates_meta():
    pdf = pd.DataFrame(
        {"a": pd.Series(["a", "b", "a", "b"], dtype="string[pyarrow]"), "b": 1}
    )
    df = from_pandas(pdf, npartitions=2)
    result = df.drop_duplicates().groupby("a").size().to_frame("cnt").reset_index()
    assert result.dtypes["a"] == "string"
    expected = pdf.drop_duplicates().groupby("a").size().to_frame("cnt").reset_index()
    assert_eq(result, expected, check_index=False)


def test_setattr(df, pdf):
    df.x = df.x.astype("float64")
    pdf.x = pdf.x.astype("float64")
    assert_eq(df, pdf)


def test_rename_projection_no_renamer(df, pdf):
    result = df.rename(columns={"a": "x"})["x"]
    expected = pdf.rename(columns={"a": "x"})["x"]
    assert_eq(result, expected)


def test_reset_index_projection_drop(df, pdf):
    result = df.reset_index(drop=False)[["x"]]
    expected = pdf.reset_index(drop=False)[["x"]]
    assert_eq(result, expected, check_index=False)

    pdf = pdf.set_index("x")["y"]
    df = from_pandas(pdf, npartitions=10)
    result = df.reset_index(drop=False)
    result = result[result.x > 5]
    expected = pdf.reset_index(drop=False)
    expected = expected[expected.x > 5]
    assert_eq(result, expected, check_index=False)


def test_setitem_triggering_realign():
    a = from_pandas(pd.DataFrame({"A": range(12)}), npartitions=3)
    b = from_pandas(pd.Series(range(12), name="B"), npartitions=4)
    a["C"] = b
    assert len(a) == 12


def test_is_monotonic_dt64():
    s = pd.Series(pd.date_range("20130101", periods=10))
    ds = from_pandas(s, npartitions=5)
    assert_eq(s.is_monotonic_increasing, ds.is_monotonic_increasing)
    assert_eq(s.is_monotonic_decreasing, ds.is_monotonic_decreasing)


@pytest.mark.parametrize("col_type", [list, np.array, pd.Series, pd.Index])
def test_getitem_column_types(col_type, df, pdf):
    cols = col_type(["x", "y"])
    assert_eq(df[cols], pdf[cols])


def test_enforce_runtime_divisions():
    pdf = pd.DataFrame({"x": range(50)})
    ddf = from_pandas(pdf, 5)
    # Default divisions should be correct
    assert_eq(pdf, ddf.enforce_runtime_divisions())


def test_apply_infer_columns():
    df = pd.DataFrame({"x": [1, 2, 3, 4], "y": [10, 20, 30, 40]})
    ddf = from_pandas(df, npartitions=2)

    def return_df(x):
        return pd.Series([x.sum(), x.mean()], index=["sum", "mean"])

    with pytest.warns(UserWarning, match="metadata"):
        result = ddf.apply(return_df, axis=1)
    assert_eq(result.columns, pd.Index(["sum", "mean"]))
    assert_eq(result, df.apply(return_df, axis=1))


@pytest.mark.parametrize("fuse", [True, False])
def test_tree_repr(fuse):
    s = from_pandas(pd.Series(range(10))).expr.tree_repr()
    assert ("<pandas>" in s) or ("<series>" in s)

    df = timeseries()
    expr = ((df.x + 1).sum(skipna=False) + df.y.mean()).expr

    # Check result before optimization
    s = expr.tree_repr()
    assert "Sum:" in s
    assert "Add:" in s
    assert "Mean:" in s
    assert "ArrowStringConversion" in s
    assert "AlignPartitions:" not in s
    assert str(df.frame.seed) in s.lower()

    # Check result after optimization
    optimized = expr.optimize(fuse=fuse)
    s = str(optimized.tree_repr())
    assert "Sum(Chunk):" in s
    assert "Sum(TreeReduce): split_every=False" in s
    assert "Add:" in s
    assert "Mean:" not in s
    assert "AlignPartitions:" not in s
    assert "True" not in s
    assert "None" not in s
    assert "skipna=False" in s
    assert str(df.frame.seed) in s.lower()
    if fuse:
        assert "Fused" in s
        assert "|" in s


def test_random_partitions(df, pdf):
    a, b = df.random_split([0.5, 0.5], 42)
    assert isinstance(a, DataFrame)
    assert isinstance(b, DataFrame)
    assert a._name != b._name
    np.testing.assert_array_equal(a.index, sorted(a.index))

    assert len(a.compute()) + len(b.compute()) == len(pdf)
    a2, b2 = df.random_split([0.5, 0.5], 42)
    assert a2._name == a._name
    assert b2._name == b._name

    a, b = df.random_split([0.5, 0.5], 42, True)
    a2, b2 = df.random_split([0.5, 0.5], 42, True)
    assert_eq(a, a2)
    assert_eq(b, b2)
    with pytest.raises(AssertionError):
        np.testing.assert_array_equal(a.index, sorted(a.index))

    parts = df.random_split([0.4, 0.5, 0.1], 42)
    names = {p._name for p in parts}
    names.update([a._name, b._name])
    assert len(names) == 5

    with pytest.raises(ValueError):
        df.random_split([0.4, 0.5], 42)

    a, b = df.x.random_split([0.5, 0.5], 42, True)
    a2, b2 = df.x.random_split([0.5, 0.5], 42, True)
    assert_eq(a, a2)
    assert_eq(b, b2)
    assert a.ndim == 1
    assert b.ndim == 1


def test_simple_graphs(df):
    expr = (df + 1).expr
    graph = expr.__dask_graph__()

    assert graph[(expr._name, 0)] == (operator.add, (df.expr._name, 0), 1)


def test_values():
    from dask.array.utils import assert_eq

    pdf = pd.DataFrame(
        {"x": ["a", "b", "c", "d"], "y": [2, 3, 4, 5]},
        index=pd.Index([1.0, 2.0, 3.0, 4.0], name="ind"),
    )

    df = from_pandas(pdf, 2)

    assert_eq(df.values, pdf.values)
    assert_eq(df.x.values, pdf.x.values)
    assert_eq(df.y.values, pdf.y.values)
    assert_eq(df.index.values, pdf.index.values)


def test_depth(df):
    assert df._depth() == 1
    assert (df + 1)._depth() == 2
    assert ((df.x + 1) + df.y)._depth() == 4


def test_partitions_nested(df):
    a = expr.Partitions(expr.Partitions(df.expr, [2, 4, 6]), [0, 2])
    b = expr.Partitions(df.expr, [2, 6])

    assert a.optimize()._name == b.optimize()._name


@pytest.mark.parametrize("sort", [True, False])
@pytest.mark.parametrize("npartitions", [7, 12])
def test_repartition_npartitions(pdf, npartitions, sort):
    df = from_pandas(pdf, sort=sort) + 1
    df2 = df.repartition(npartitions=npartitions)
    assert df2.npartitions == npartitions
    assert_eq(df, df2)


@pytest.mark.parametrize("opt", [True, False])
def test_repartition_divisions(df, opt):
    end = df.divisions[-1] + 100
    stride = end // (df.npartitions + 2)
    divisions = tuple(range(0, end, stride))
    df2 = (df + 1).repartition(divisions=divisions, force=True)["x"]
    df2 = optimize(df2) if opt else df2
    assert df2.divisions == divisions
    assert_eq((df + 1)["x"], df2)

    # Check partitions
    for p, part in enumerate(dask.compute(list(df2.index.partitions))[0]):
        if len(part):
            assert part.min() >= df2.divisions[p]
            assert part.max() < df2.divisions[p + 1]


def test_repartition_no_op(df):
    result = df.repartition(divisions=df.divisions).optimize()
    assert result._name == df._name


def test_repartition_partition_size(df):
    df2 = df.repartition(partition_size="0.25kb")
    assert df2.npartitions == 20
    assert_eq(df, df2, check_divisions=False)
    assert all(div is None for div in df2.divisions)

    df2 = df.repartition(partition_size="1kb")
    assert df2.npartitions == 4
    assert_eq(df, df2)
    assert all(div is not None for div in df2.divisions)


def test_len(df, pdf):
    df2 = df[["x"]] + 1
    assert len(df2) == len(pdf)

    assert len(df[df.x > 5]) == len(pdf[pdf.x > 5])

    first = df2.partitions[0].compute()
    assert len(df2.partitions[0]) == len(first)

    assert isinstance(Len(df2.expr).optimize(), expr.Literal)
    assert isinstance(expr.Lengths(df2.expr).optimize(), expr.Literal)


def test_astype_simplify(df, pdf):
    q = df.astype({"x": "float64", "y": "float64"})["x"]
    result = q.simplify()
    expected = df["x"].simplify().astype({"x": "float64"})
    assert result._name == expected._name
    assert_eq(q, pdf.astype({"x": "float64", "y": "float64"})["x"])

    q = df.astype({"y": "float64"})["x"]
    result = q.simplify()
    expected = df["x"].simplify()
    assert result._name == expected._name

    q = df.astype("float64")["x"]
    result = q.simplify()
    expected = df["x"].simplify().astype("float64")
    assert result._name == expected._name


@pytest.mark.parametrize("split_out", [1, True])
def test_drop_duplicates(df, pdf, split_out):
    with dask.config.set({"dataframe.shuffle.method": "tasks"}):
        assert_eq(
            df.drop_duplicates(split_out=split_out),
            pdf.drop_duplicates(),
        )
        assert_eq(
            df.drop_duplicates(ignore_index=True, split_out=split_out),
            pdf.drop_duplicates(ignore_index=True),
            check_index=split_out is not True,
        )
        assert_eq(
            df.drop_duplicates(subset=["y"], split_out=split_out),
            pdf.drop_duplicates(subset=["y"]),
        )
        assert_eq(
            df.drop_duplicates(subset=["y"], split_out=split_out, keep="last"),
            pdf.drop_duplicates(subset=["y"], keep="last"),
        )
        assert_eq(
            df.y.drop_duplicates(split_out=split_out),
            pdf.y.drop_duplicates(),
        )
        assert_eq(
            df.y.drop_duplicates(split_out=split_out, keep="last"),
            pdf.y.drop_duplicates(keep="last"),
        )
        actual = df.set_index("y").index.drop_duplicates(split_out=split_out)
        if split_out is True:
            actual = actual.compute().sort_values()  # shuffle is unordered
        assert_eq(
            actual,
            pdf.set_index("y").index.drop_duplicates(),
        )

    with pytest.raises(KeyError, match="'a'"):
        df.drop_duplicates(subset=["a"], split_out=split_out)

    with pytest.raises(TypeError, match="got an unexpected keyword argument"):
        df.x.drop_duplicates(subset=["a"], split_out=split_out)

    with pytest.raises(NotImplementedError, match="with keep=False"):
        df.x.drop_duplicates(keep=False)


def test_drop_duplicates_split_out(df, pdf):
    q = df.drop_duplicates(subset=["x"])
    assert len(list(q.optimize().find_operations(Shuffle))) > 0
    assert_eq(q, pdf.drop_duplicates(subset=["x"]))

    q = df.x.drop_duplicates()
    assert len(list(q.optimize().find_operations(Shuffle))) > 0
    assert_eq(q, pdf.x.drop_duplicates())


def test_walk(df):
    df2 = df[df["x"] > 1][["y"]] + 1
    assert all(isinstance(ex, expr.Expr) for ex in df2.walk())
    exprs = {e._name for e in set(df2.walk())}
    assert df.expr._name in exprs
    assert df["x"].expr._name in exprs
    assert (df["x"] > 1).expr._name in exprs
    assert 1 not in exprs


def test_find_operations(df):
    df2 = df[df["x"] > 1][["y"]] + 1

    filters = list(df2.find_operations(expr.Filter))
    assert len(filters) == 1

    projections = list(df2.find_operations(expr.Projection))
    assert len(projections) == 2

    adds = list(df2.find_operations(expr.Add))
    assert len(adds) == 1
    assert next(iter(adds))._name == df2._name

    both = list(df2.find_operations((expr.Add, expr.Filter)))
    assert len(both) == 2


@pytest.mark.parametrize("subset", ["x", ["x"]])
def test_dropna_simplify(pdf, subset):
    pdf["z"] = 1
    df = from_pandas(pdf)
    q = df.dropna(subset=subset)["y"]
    result = q.simplify()
    expected = df[["x", "y"]].simplify().dropna(subset=subset)["y"]
    assert result._name == expected._name
    assert_eq(q, pdf.dropna(subset=subset)["y"])


def test_dir(df):
    assert all(c in dir(df) for c in df.columns)
    assert "sum" in dir(df)
    assert "sum" in dir(df.x)
    assert "sum" in dir(df.index)


@pytest.mark.parametrize(
    "func, args",
    [
        ("replace", (1, 2)),
        ("isin", ([1, 2],)),
        ("clip", (0, 5)),
        ("isna", ()),
        ("round", ()),
        ("abs", ()),
        ("fillna", ({"x": 1})),
        # ("map", (lambda x: x+1, )),  # add in when pandas 2.1 is out
    ],
)
@pytest.mark.parametrize("indexer", ["x", ["x"]])
def test_simplify_up_blockwise(df, pdf, func, args, indexer):
    q = getattr(df, func)(*args)[indexer]
    result = q.simplify()
    expected = getattr(df[indexer].simplify(), func)(*args)
    assert result._name == expected._name

    assert_eq(q, getattr(pdf, func)(*args)[indexer])

    q = getattr(df, func)(*args)[["x", "y"]]
    result = q.simplify()
    expected = getattr(df.simplify(), func)(*args)
    assert result._name == expected._name


def test_isin_as_predicate(df, pdf):
    result = df[df.x.isin([10])]
    assert_eq(result, pdf[pdf.x.isin([10])])


def test_sample(df):
    result = df.sample(frac=0.5)

    assert_eq(result, result)

    result = df.sample(frac=0.5, random_state=1234)
    expected = df.sample(frac=0.5, random_state=1234)
    assert_eq(result, expected)


@xfail_gpu("align not supported by cudf")
def test_align(df, pdf):
    result_1, result_2 = df.align(df)
    pdf_result_1, pdf_result_2 = pdf.align(pdf)
    assert_eq(result_1, pdf_result_1)
    assert_eq(result_2, pdf_result_2)

    result_1, result_2 = df.x.align(df.x)
    pdf_result_1, pdf_result_2 = pdf.x.align(pdf.x)
    assert_eq(result_1, pdf_result_1)
    assert_eq(result_2, pdf_result_2)


@xfail_gpu("align not supported by cudf")
def test_align_different_partitions():
    pdf = pd.DataFrame({"a": [11, 12, 31, 1, 2, 3], "b": [1, 2, 3, 4, 5, 6]})
    df = from_pandas(pdf, npartitions=2)
    pdf2 = pd.DataFrame(
        {"a": [11, 12, 31, 1, 2, 3], "b": [1, 2, 3, 4, 5, 6]},
        index=[-2, -1, 0, 1, 2, 3],
    )
    df2 = from_pandas(pdf2, npartitions=2)
    result_1, result_2 = df.align(df2)
    pdf_result_1, pdf_result_2 = pdf.align(pdf2)
    assert_eq(result_1, pdf_result_1)
    assert_eq(result_2, pdf_result_2)


@xfail_gpu("align not supported by cudf")
def test_align_unknown_partitions_same_root():
    pdf = pd.DataFrame({"a": 1}, index=[3, 2, 1])
    df = from_pandas(pdf, npartitions=2, sort=False)
    result_1, result_2 = df.align(df)
    pdf_result_1, pdf_result_2 = pdf.align(pdf)
    assert_eq(result_1, pdf_result_1)
    assert_eq(result_2, pdf_result_2)


@xfail_gpu(reason="align not supported by cudf")
def test_unknown_partitions_different_root():
    pdf = pd.DataFrame({"a": 1}, index=[3, 2, 1])
    df = from_pandas(pdf, npartitions=2, sort=False)
    pdf2 = pd.DataFrame({"a": 1}, index=[4, 3, 2, 1])
    df2 = from_pandas(pdf2, npartitions=2, sort=False)
    result = df.align(df2)[0].optimize()
    assert len(list(result.find_operations(Shuffle))) > 0
    assert_eq(result, pdf.align(pdf2)[0])


@pytest.mark.parametrize("split_every", [None, 2])
def test_split_out_drop_duplicates(split_every):
    x = np.concatenate([np.arange(10)] * 100)[:, None]
    y = x.copy()
    z = np.concatenate([np.arange(20)] * 50)[:, None]
    rs = np.random.RandomState(1)
    rs.shuffle(x)
    rs.shuffle(y)
    rs.shuffle(z)
    df = pd.DataFrame(np.concatenate([x, y, z], axis=1), columns=["x", "y", "z"])
    ddf = from_pandas(df, npartitions=20)

    sol = df.drop_duplicates(subset=["x", "z"], keep="first")
    res = ddf.drop_duplicates(
        subset=["x", "z"], keep="first", split_every=split_every, split_out=10
    )
    assert res.npartitions == 10
    assert_eq(sol, res, check_index=False)


@pytest.mark.parametrize("dropna", [False, True])
def test_nunique(pdf, dropna):
    pdf["z"] = pdf.y.astype(float)
    pdf.loc[9:12, "z"] = np.nan  # Spans two partitions
    df = from_pandas(pdf, npartitions=10)

    assert_eq(
        df.nunique(dropna=dropna),
        pdf.nunique(dropna=dropna),
    )
    assert_eq(
        df.nunique(axis=1, dropna=dropna),
        pdf.nunique(axis=1, dropna=dropna),
    )
    assert_eq(
        df.z.nunique(dropna=dropna),
        pdf.z.nunique(dropna=dropna),
    )
    assert_eq(
        df.set_index("z").index.nunique(dropna=dropna),
        pdf.set_index("z").index.nunique(dropna=dropna),
    )


@xfail_gpu("compute_hll_array doesn't work for cudf")
def test_nunique_approx(df, pdf):
    actual = df.nunique_approx().compute()
    assert 99 < actual < 101

    actual = df.y.nunique_approx().compute()
    expect = pdf.y.nunique()
    assert expect * 0.99 < actual < expect * 1.01

    actual = df.set_index("y").index.nunique_approx().compute()
    expect = pdf.set_index("y").index.nunique()
    assert expect * 0.99 < actual < expect * 1.01


def test_memory_usage_per_partition(df):
    expected = pd.Series(part.compute().memory_usage().sum() for part in df.partitions)
    result = df.memory_usage_per_partition()
    assert_eq(expected, result, check_index=False)

    expected = pd.Series(part.x.compute().memory_usage() for part in df.partitions)
    result = df.x.memory_usage_per_partition()
    assert_eq(expected, result, check_index=False)


def test_assign_simplify(pdf):
    df = from_pandas(pdf)
    df2 = from_pandas(pdf)
    df["new"] = df.x > 1
    result = df[["x", "new"]].simplify()
    expected = df2[["x"]].assign(new=df2.x > 1).simplify()
    assert result._name == expected._name

    pdf["new"] = pdf.x > 1
    assert_eq(pdf[["x", "new"]], result)


def test_assign_simplify_new_column_not_needed(pdf):
    df = from_pandas(pdf)
    df2 = from_pandas(pdf)
    df["new"] = df.x > 1
    result = df[["x"]].simplify()
    expected = df2[["x"]].simplify()
    assert result._name == expected._name

    pdf["new"] = pdf.x > 1
    assert_eq(result, pdf[["x"]])


def test_assign_simplify_series(pdf):
    df = from_pandas(pdf)
    df2 = from_pandas(pdf)
    df["new"] = df.x > 1
    result = df.new.simplify()
    expected = df2[[]].assign(new=df2.x > 1).new.simplify()
    assert result._name == expected._name


@xfail_gpu("assign function not supported by cudf")
def test_assign_non_series_inputs(df, pdf):
    assert_eq(df.assign(a=lambda x: x.x * 2), pdf.assign(a=lambda x: x.x * 2))
    assert_eq(df.assign(a=2), pdf.assign(a=2))
    assert_eq(df.assign(a=df.x.sum()), pdf.assign(a=pdf.x.sum()))

    assert_eq(df.assign(a=lambda x: x.x * 2).y, pdf.assign(a=lambda x: x.x * 2).y)
    assert_eq(df.assign(a=lambda x: x.x * 2).a, pdf.assign(a=lambda x: x.x * 2).a)


def test_assign_squash_together(df, pdf):
    df["a"] = 1
    df["b"] = 2
    result = df.simplify()
    assert len([x for x in list(result.expr.walk()) if isinstance(x, expr.Assign)]) == 1
    pdf["a"] = 1
    pdf["b"] = 2
    assert_eq(df, pdf)
    assert "Assign: a=1, b=2" in [line for line in result.expr._tree_repr_lines()]


def test_rename_series_reduction(pdf, df):
    result = df[["x"]].rename(columns={"x": "a"})["a"]
    expected = pdf[["x"]].rename(columns={"x": "a"})["a"]
    assert_eq(result, expected)


def test_are_co_aligned(pdf, df):
    df2 = df.reset_index()
    assert are_co_aligned(df.expr, df2.expr)
    assert are_co_aligned(df.expr, df2.sum().expr)
    assert not are_co_aligned(df.expr, df2.repartition(npartitions=2).expr)

    assert are_co_aligned(df.expr, df.sum().expr)
    assert are_co_aligned((df + df.sum()).expr, df.sum().expr)

    pdf = pdf.assign(z=1)
    df3 = from_pandas(pdf, npartitions=10)
    assert not are_co_aligned(df.expr, df3.expr)
    assert not are_co_aligned(df.expr, df3.sum().expr)

    merged = df.merge(df2)
    merged_first = merged.reset_index()
    merged_second = merged.rename(columns={"x": "a"})
    assert are_co_aligned(merged_first.expr, merged_second.expr)
    assert not are_co_aligned(merged_first.expr, df.expr)


def test_assign_pandas_inputs(df, pdf):
    assert_eq(df.assign(a=pdf.x), pdf.assign(a=pdf.x))


@xfail_gpu()
def test_astype_categories(df):
    result = df.astype("category")
    assert_eq(result.x._meta.cat.categories, pd.Index([UNKNOWN_CATEGORIES]))
    assert_eq(result.y._meta.cat.categories, pd.Index([UNKNOWN_CATEGORIES]))


def test_drop_simplify(df):
    q = df.drop(columns=["x"])[["y"]]
    result = q.simplify()
    expected = df[["y"]].simplify()
    assert result._name == expected._name


def test_op_align():
    pdf = pd.DataFrame({"x": [1, 2, 3], "y": 1})
    df = from_pandas(pdf, npartitions=2)

    pdf2 = pd.DataFrame({"x": [1, 2, 3, 4, 5, 6], "y": 1})
    df2 = from_pandas(pdf2, npartitions=2)

    assert_eq(df - df2, pdf - pdf2)


def test_can_co_align(df, pdf):
    q = (df.x + df.y).optimize(fuse=False)
    assert_eq(q, pdf.x + pdf.y)

    pdf["z"] = 100
    df2 = from_pandas(pdf, npartitions=df.npartitions * 2)
    assert df.npartitions != df2.npartitions
    assert_eq(df.x + df.y, pdf.x + pdf.y)


def test_avoid_alignment():
    a = pd.DataFrame({"x": range(100)})
    da = from_pandas(a, npartitions=4)

    b = pd.DataFrame({"y": range(100)})
    b["z"] = b.y * 2
    db = from_pandas(b, npartitions=3)

    # Give correct results even when misaligned
    assert_eq(a.x + b.y, da.x + db.y)

    assert not any(isinstance(ex, OpAlignPartitions) for ex in (db.y + db.z).walk())
    assert not any(
        isinstance(ex, OpAlignPartitions) for ex in (da.x + db.y.sum()).walk()
    )


def test_mixed_array_op(df, pdf):
    assert_eq(df.x + df.y.values, pdf.x + pdf.y.values)
    assert_eq(df + df.values, pdf + pdf.values)


@pytest.mark.parametrize(
    "binop",
    [
        operator.add,
        operator.sub,
        operator.mul,
        operator.truediv,
        operator.pow,
        operator.mod,
    ],
)
def test_array_series_comp(binop):
    data = [1.0, 2.0, 3.0, 4.0]
    pd_data = pd.Series(data)
    d_series = from_pandas(pd.Series(data), npartitions=2)
    d_array = da.from_array(data, chunks=2)

    expected = binop(pd_data, pd_data)
    for left, right in [(d_series, d_array), (d_array, d_series)]:
        res = binop(left, right)
        assert_eq(res, expected)


def test_len_shuffle_repartition(df, pdf):
    df2 = df.set_index("x")
    assert isinstance(Len(df2.expr).optimize(), expr.Literal)
    result = len(df2)
    assert result == len(pdf.set_index("x"))

    df2 = df.repartition(npartitions=3)
    assert isinstance(Len(df2.expr).optimize(), expr.Literal)
    result = len(df2)
    assert result == len(df)

    df2 = df.shuffle("x")
    assert isinstance(Len(df2.expr).optimize(), expr.Literal)
    result = len(df2)
    assert result == len(df)


def test_columns_setter(df, pdf):
    df.columns = ["a", "b"]
    result = df[["a"]]
    pdf.columns = ["a", "b"]
    expecetd = pdf[["a"]]
    assert_eq(result, expecetd)

    with pytest.raises(ValueError, match="Length mismatch"):
        df.columns = [1, 2, 3]


def test_contains(df):
    assert "x" in df
    with pytest.raises(NotImplementedError, match="Using 'in' to test for membership"):
        1 in df.x  # noqa: B015


def test_filter_pushdown_unavailable(df):
    df = df.rename_axis(index="hello")
    result = df[df.x > 5] + df.x.sum()
    assert result.simplify()._name == result._name

    result = df[df.x > 5] + df.x.sum()
    result = result[["x"]]
    expected = df[["x"]][df.x > 5] + df.x.sum()
    assert result.simplify()._name == expected.simplify()._name


def test_filter_pushdown(df, pdf):
    indexer = df.x > 5
    result = df.rename_axis(index="hello")[indexer].optimize(fuse=False)
    expected = df[indexer].rename_axis(index="hello")
    assert result._name == expected._name

    df = df.rename_axis(index="hello")
    result = df[df.x > 5].simplify()
    assert result._name == expected._name

    pdf["z"] = 1
    df = from_pandas(pdf, npartitions=10)
    df2 = df.rename_axis(index="hello")
    result = df2[df2.x > 5][["x", "y"]].simplify()
    df_opt = df[["x", "y"]]
    expected = df_opt[df_opt.x > 5].rename_axis(index="hello").simplify()
    assert result._name == expected._name


def test_shape(df, pdf):
    result = df.shape
    assert result[0]._name == (df.size // 2)._name
    assert assert_eq(result[0], pdf.shape[0])
    assert result[1] == pdf.shape[1]

    result = df.x.shape
    assert result[0]._name == (df.x.size)._name
    assert assert_eq(result[0], pdf.shape[0])

    result = df[[]].shape
    assert assert_eq(result[0], pdf[[]].shape[0])
    assert assert_eq(result[1], pdf[[]].shape[1])


def test_size(df, pdf):
    assert_eq(df.size, pdf.size)


def test_drop_duplicates_groupby(pdf):
    pdf["z"] = 1
    df = from_pandas(pdf, npartitions=10)
    df = df.drop_duplicates(subset="x")
    query = df.groupby("y").z.count()
    expected = pdf.drop_duplicates(subset="x").groupby("y").z.count()
    assert_eq(query, expected)


def test_expression_bool_raises(df):
    with pytest.raises(ValueError, match="The truth value"):
        bool(df.expr)


def test_expr_is_scalar(df):
    assert not is_scalar(df.expr)
    with pytest.raises(ValueError, match="The truth value"):
        df.expr.x in df.expr.columns  # noqa: B015


def test_replace_filtered_combine_similar():
    from dask_expr._expr import Filter, Replace

    pdf = pd.DataFrame({"a": [1, 2, 3, 4, 5, 6], "b": 1, "c": 2})

    df = from_pandas(pdf.copy(), npartitions=2)
    df = df[df.a > 3]
    df = df.replace(5, 4)
    df["new"] = df.a + df.b

    pdf = pdf[pdf.a > 3]
    pdf = pdf.replace(5, 4)
    pdf["new"] = pdf.a + pdf.b

    df = df.optimize(fuse=False)
    assert_eq(df, pdf)  # Check result

    # Check that Replace expressions always operate on
    # Filter expressions (and not the other way around)
    similar = list(df.find_operations(Replace))
    assert all(isinstance(op.frame, Filter) for op in similar)


def test_quantile_frame(df, pdf):
    assert_eq(df.quantile(), pd.Series([49.0, 7.0], index=["x", "y"], name=0.5))
    assert df.quantile().divisions == ("x", "y")
    assert_eq(df.quantile(q=[0.5]), pd.DataFrame({"x": [49.0], "y": 7.0}, index=[0.5]))
    assert_eq(
        df.quantile(q=[0.5], numeric_only=True),
        pd.DataFrame({"x": [49.0], "y": 7.0}, index=[0.5]),
    )

    pdf["z"] = 1
    df = from_pandas(pdf, npartitions=10)
    q = df.quantile(q=[0.5])[["x", "z"]]
    assert q.optimize()._name == df[["x", "z"]].quantile(q=[0.5]).optimize()._name

    q = df.quantile(q=0.5)[["x", "z"]]
    assert (
        q.optimize()._name
        == df[["x", "z"]].quantile(q=0.5)[["x", "z"]].optimize()._name
    )
    assert_eq(df.quantile(axis=1), pdf.quantile(axis=1))


def test_combine():
    df1 = pd.DataFrame(
        {
            "A": np.random.choice([1, 2, np.nan], 100),
            "B": np.random.choice(["a", "b", "nan"], 100),
        }
    )

    df2 = pd.DataFrame(
        {
            "A": np.random.choice([1, 2, 3], 100),
            "B": np.random.choice(["a", "b", "c"], 100),
        }
    )
    ddf1 = from_pandas(df1, 4)
    ddf2 = from_pandas(df2, 5)

    first = lambda a, b: a

    # You can add series with strings and nans but you can't add scalars 'a' + np.nan
    str_add = lambda a, b: a + b if a is not np.nan else a

    # DataFrame
    for dda, ddb, a, b, runs in [
        # (ddf1, ddf2, df1, df2, [(add, None), (first, None)]),
        (ddf1.A, ddf2.A, df1.A, df2.A, [(add, None), (add, 100), (first, None)]),
        (
            ddf1.B,
            ddf2.B,
            df1.B,
            df2.B,
            [(str_add, None), (str_add, "d"), (first, None)],
        ),
    ]:
        for func, fill_value in runs:
            sol = a.combine(b, func, fill_value=fill_value)
            assert_eq(dda.combine(ddb, func, fill_value=fill_value), sol)
            assert_eq(dda.combine(b, func, fill_value=fill_value), sol)

    assert_eq(
        ddf1.combine(ddf2, add, overwrite=False), df1.combine(df2, add, overwrite=False)
    )
    assert dda.combine(ddb, add)._name == dda.combine(ddb, add)._name


def test_quantile(df):
    assert_eq(df.x.quantile(), 49.0)
    assert_eq(df.x.quantile(method="dask"), 49.0)
    assert_eq(
        df.x.quantile(q=[0.2, 0.8]),
        pd.Series([19.0, 79.0], index=[0.2, 0.8], name="x"),
    )
    assert_eq(
        df.x.index.quantile(q=[0.2, 0.8]),
        pd.Series([19.0, 79.0], index=[0.2, 0.8]),
    )

    with pytest.raises(AssertionError):
        df.x.quantile(q=[]).compute()

    ser = from_pandas(pd.Series(["a", "b", "c"]), npartitions=2)
    with pytest.raises(ValueError, match="not supported with string series"):
        ser.quantile()


@pytest.mark.parametrize("join", ["inner", "outer", "left", "right"])
def test_align_axis(join):
    df1a = pd.DataFrame(
        {"A": np.random.randn(10), "B": np.random.randn(10), "C": np.random.randn(10)},
        index=[1, 12, 5, 6, 3, 9, 10, 4, 13, 11],
    )

    df1b = pd.DataFrame(
        {"B": np.random.randn(10), "C": np.random.randn(10), "D": np.random.randn(10)},
        index=[0, 3, 2, 10, 5, 6, 7, 8, 12, 13],
    )
    ddf1a = from_pandas(df1a, 3)
    ddf1b = from_pandas(df1b, 3)

    res1, res2 = ddf1a.align(ddf1b, join=join, axis=0)
    exp1, exp2 = df1a.align(df1b, join=join, axis=0)
    assert assert_eq(res1, exp1)
    assert assert_eq(res2, exp2)

    res1, res2 = ddf1a.align(ddf1b, join=join, axis=1)
    exp1, exp2 = df1a.align(df1b, join=join, axis=1)
    assert assert_eq(res1, exp1)
    assert assert_eq(res2, exp2)

    res1, res2 = ddf1a.align(ddf1b, join=join, axis="index")
    exp1, exp2 = df1a.align(df1b, join=join, axis="index")
    assert assert_eq(res1, exp1)
    assert assert_eq(res2, exp2)

    res1, res2 = ddf1a.align(ddf1b, join=join, axis="columns")
    exp1, exp2 = df1a.align(df1b, join=join, axis="columns")
    assert assert_eq(res1, exp1)
    assert assert_eq(res2, exp2)

    # invalid
    with pytest.raises(ValueError):
        ddf1a.align(ddf1b, join=join, axis="XXX")

    with pytest.raises(ValueError):
        ddf1a["A"].align(ddf1b["B"], join=join, axis=1)


def test_quantile_datetime_numeric_only_false():
    df = pd.DataFrame(
        {
            "int": [1, 2, 3, 4, 5, 6, 7, 8],
            "dt": [pd.NaT] + [datetime(2011, i, 1) for i in range(1, 8)],
            "timedelta": pd.to_timedelta([1, 2, 3, 4, 5, 6, 7, np.nan]),
        }
    )
    ddf = from_pandas(df, 1)

    assert_eq(ddf.quantile(numeric_only=False), df.quantile(numeric_only=False))


def test_dtype(df, pdf):
    assert df.x.dtype == pdf.x.dtype
    assert df.index.dtype == pdf.index.dtype
    assert_eq(df.dtypes, pdf.dtypes)


def test_isnull():
    pdf = pd.DataFrame(
        {
            "A": range(10),
            "B": [None] * 10,
            "C": [1] * 4 + [None] * 4 + [2] * 2,
        }
    )
    df = from_pandas(pdf, npartitions=2)
    assert_eq(df.notnull(), pdf.notnull())
    assert_eq(df.isnull(), pdf.isnull())
    for c in pdf.columns:
        assert_eq(df[c].isnull(), pdf[c].isnull())


def test_scalar_to_series():
    sc = from_pandas(pd.Series([1])).sum()
    ss1 = sc.to_series()
    ss2 = sc.to_series("xxx")
    assert_eq(ss1, pd.Series([1]))
    assert_eq(ss2, pd.Series([1], index=["xxx"]))


@pytest.mark.parametrize("data_freq, divs1", [("B", False), ("D", True), ("h", True)])
def test_shift_with_freq_datetime(pdf, data_freq, divs1):
    pdf.index = pd.date_range(start="2020-01-01", periods=len(pdf), freq=data_freq)
    df = from_pandas(pdf, npartitions=4)
    for freq, divs2 in [("s", True), ("W", False), (pd.Timedelta(10, unit="h"), True)]:
        for d, p in [(df, pdf), (df.x, pdf.x)]:
            res = d.shift(2, freq=freq)
            assert_eq(res, p.shift(2, freq=freq))
            assert res.known_divisions == divs2

    res = df.index.shift(2)
    assert_eq(res, df.index.shift(2))
    assert res.known_divisions == divs1


def test_isin_head(df, pdf):
    df["foo"] = df.x.isin([1, 2])
    pdf["foo"] = pdf.x.isin([1, 2])
    assert_eq(df.head(), pdf.head())


def test_head_npartitions_divisions(pdf):
    df = from_pandas(pdf, npartitions=1)
    assert_eq(df.head(3, compute=False), pdf.head(3))


@pytest.mark.parametrize("data_freq,divs", [("D", True), ("h", True)])
def test_shift_with_freq_period_index(pdf, data_freq, divs):
    pdf.index = pd.period_range(start="2020-01-01", periods=len(pdf), freq=data_freq)
    df = from_pandas(pdf, npartitions=4)
    for d, p in [(df, pdf), (df.x, pdf.x)]:
        res = d.shift(2, freq=data_freq)
        assert_eq(res, p.shift(2, freq=data_freq))
        assert res.known_divisions == divs
    res = df.index.shift(2)
    assert_eq(res, df.index.shift(2))
    assert res.known_divisions == divs

    with pytest.raises(TypeError, match="argument is not supported"):
        df.index.shift(2, freq="D")


@pytest.mark.parametrize("data_freq", ["min", "D", "h"])
def test_shift_with_freq_TimedeltaIndex(pdf, data_freq):
    pdf.index = pd.timedelta_range("1 day", periods=len(pdf), freq=data_freq)
    df = from_pandas(pdf, npartitions=4)
    for freq in ["s", pd.Timedelta(10, unit="h")]:
        for d, p in [(df, pdf), (df.x, pdf.x), (df.index, pdf.index)]:
            res = d.shift(2, freq=freq)
            assert_eq(res, p.shift(2, freq=freq))
            assert res.known_divisions
    # Index shifts also work with freq=None
    res = df.index.shift(2)
    assert_eq(res, df.index.shift(2))
    assert res.known_divisions


def test_iter(df, pdf):
    assert_eq(list(df), list(pdf))  # column names


def test_items(df, pdf):
    expect = list(pdf.items())
    actual = list(df.items())
    assert len(expect) == len(actual)
    for (expect_name, expect_col), (actual_name, actual_col) in zip(expect, actual):
        assert expect_name == actual_name
        assert_eq(expect_col, actual_col)


def test_isin_strings():
    pdf = pd.DataFrame({"foo": ["1", "2", "3"]})
    df = from_pandas(pdf)
    assert_eq(df.foo.isin(["1", "2"]), pdf.foo.isin(["1", "2"]))


def test_predicate_pushdown_ndim_change(df, pdf):
    result = df.sum().to_frame()
    result = result[result[0] > 1]
    expected = pdf.sum().to_frame()
    expected = expected[expected[0] > 1]
    assert_eq(result, expected)
    assert isinstance(result.simplify().expr.frame, Filter)
    assert isinstance(result.simplify().expr, ToFrame)


def test_axes(df, pdf):
    assert len(df.axes) == len(pdf.axes)
    [assert_eq(d, p) for d, p in zip(df.axes, pdf.axes)]
    assert len(df.x.axes) == len(pdf.x.axes)
    assert_eq(df.x.axes[0], pdf.x.axes[0])


def test_filter_optimize_condition():
    pdf = pd.DataFrame({"a": [1, 2, 3, 4], "b": [True, False, True, False]})
    df = from_pandas(pdf, npartitions=2)
    result = df[df.b.fillna(True)]
    expected = pdf[pdf.b.fillna(True)]
    assert_eq(result, expected)


def test_scalar_repr(df):
    result = repr(df.size)
    assert result == "<dask_expr.expr.Scalar: expr=df.size(), dtype=int64>"


def test_array_conversion(df, pdf):
    import dask.array as da

    result = df.map_partitions(lambda x: np.asarray(x))
    expected = np.asarray(pdf)
    da.utils.assert_eq(result, expected)


def test_reset_index_filter_pushdown(df, pdf):
    q = df.reset_index()
    result = q[q.x > 5]
    expected = df[df.x > 5].reset_index()
    assert result.simplify()._name == expected._name

    # We are accessing the index, so don't do anything
    result = q[q["index"] > 5]
    expected = pdf.reset_index()
    expected = expected[expected["index"] > 5]
    assert_eq(result, expected, check_index=False)

    q = df.x.reset_index(drop=True)
    result = q[q > 5]
    expected = df["x"]
    expected = expected[expected > 5].reset_index(drop=True)
    assert result.simplify()._name == expected.simplify()._name

    q = df.x.reset_index()
    result = q[q.x > 5]
    expected = df["x"]
    expected = expected[expected > 5].reset_index()
    assert result.simplify()._name == expected.simplify()._name


def test_astype_filter_pushdown(df, pdf):
    result = df.astype("float64")
    result = result[result.x > 5.0]
    expected = df[df.x > 5.0].astype("float64")
    assert result.simplify()._name == expected._name

    expected = pdf.astype("float64")
    expected = expected[expected.x > 5.0]
    assert_eq(result, expected)


@pytest.mark.filterwarnings("error")
def test_warn_annotations():
    from_pandas(pd.DataFrame({"a": [1, 2, 3]}), npartitions=2)

    with pytest.warns(UserWarning, match="annotations.*retries.*ignore"):
        with dask.annotate(retries=3):
            from_pandas(pd.DataFrame({"a": [1, 2, 3]}), npartitions=2)
    # Don't warn a second time
    with dask.annotate(retries=3):
        from_pandas(pd.DataFrame({"a": [1, 2, 3]}), npartitions=2)


def test_drop_columns_with_common_prefix():
    ddf = from_pandas(
        pd.DataFrame({"prefix": [1, 2, 3], "prefix_foo": [4, 5, 6]}), npartitions=1
    )

    ddf = ddf.drop("prefix_foo", axis=1)
    assert "prefix" in ddf.optimize().columns


def test_to_datetime_repr():
    # https://github.com/dask/dask/issues/11016

    df = from_dict(
        {
            "dt": [
                "2023-01-04T00:00:00",
                "2023-04-02T00:00:00",
                "2023-01-01T00:00:00",
            ]
        },
        npartitions=1,
    )
    to_datetime_repr = repr(to_datetime(df["dt"], format="%Y-%m-%dT%H:%M:%S"))
    assert isinstance(to_datetime_repr, str)

    assert "Expr=ToDatetime(frame=df['dt']" in to_datetime_repr
    assert "%Y-%m-%dT%H:%M:%S" in to_datetime_repr


def test_drop_set(df, pdf):
    assert_eq(df.drop(columns={"x"}), pdf.drop(columns={"x"}))


def test_shape_integer(df):
    result = df.shape[0].compute()
    assert isinstance(result, int)
    assert result == 100


@pytest.mark.parametrize(
    "kwargs",
    [
        {},
        dict(id_vars="int"),
        dict(value_vars="int"),
        dict(value_vars=["obj", "int"], var_name="myvar"),
        dict(id_vars="s1", value_vars=["obj", "int"], value_name="myval"),
        dict(value_vars=["obj", "s1"]),
        dict(value_vars=["s1", "s2"]),
    ],
)
def test_melt(kwargs):
    # Duplicates `dask.dataframe.tests.test_multi.py::test_melt`,
    # but fails without `clear_divisions=True` in `melt` logic
    # (upstream test is less thorough).
    pdf = pd.DataFrame(
        {
            "obj": list("abcd") * 5,
            "s1": list("XY") * 10,
            "s2": list("abcde") * 4,
            "int": np.random.randn(20),
        }
    )
    pdf = pdf.astype({"s1": "string[pyarrow]", "s2": "string[pyarrow]"})
    ddf = from_pandas(pdf, 4)

    assert_eq(ddf.melt(**kwargs), pdf.melt(**kwargs), check_index=False)


def test_dropna_merge(df, pdf):
    dropped_na = df.dropna(subset=["x"])
    result = dropped_na.merge(dropped_na, on="x")
    expected = pdf.dropna(subset=["x"])
    expected = expected.merge(expected, on="x")
    assert_eq(result, expected, check_index=False)


def test_empty_from_pandas_projection():
    pdf = pd.DataFrame({"x": [1, 2, 3]})
    df = from_pandas(pdf, npartitions=2)
    foo = pd.Series(["a"] * 20, dtype="category")
    df["foo"] = from_pandas(foo, npartitions=1)
    pdf["foo"] = foo
    assert_eq(df["foo"], pdf["foo"])


def test_to_backend_simplify():
    with dask.config.set({"dataframe.backend": "pandas"}):
        df = from_dict({"x": [1, 2, 3], "y": [4, 5, 6]}, npartitions=2)
        df2 = df.to_backend("pandas")[["y"]]
        assert str(df2.expr) != str(df[["y"]].expr)
        df3 = df2.simplify()
        assert str(df3.expr) == str(df[["y"]].expr)