Simplify the measurement struct and refactor

Author: mnishiguchi

README.md

@@ -28,9 +28,7 @@ iex> {:ok, aht20} = AHT20.start_link(bus_name: "i2c-1", bus_address: 0x38)
 iex> AHT20.read_data(aht20)
 {:ok,
  %AHT20.Measurement{
-   raw_humidity: 158_119,
-   raw_temperature: 410_343,
-   relative_humidity: 15.079402923583984,
+   humidity_rh: 15.079402923583984,
    temperature_c: 28.26671600341797,
    temperature_f: 82.88008880615234
  }}

lib/aht20/calc.ex

@@ -6,51 +6,29 @@ defmodule AHT20.Calc do
   @doc """
   Calculates the relative humidity in percent.
 
-      iex> AHT20.Calc.relative_humidity(158119)
+      iex> AHT20.Calc.humidity_rh_from_raw(158119)
       15.079402923583984
   """
-  @spec relative_humidity(integer) :: float
-  def relative_humidity(raw_humidity), do: raw_humidity / 1_048_576.0 * 100.0
+  @spec humidity_rh_from_raw(integer) :: float
+  def humidity_rh_from_raw(raw_humidity), do: raw_humidity / 1_048_576.0 * 100.0
 
   @doc """
   Calculates the temperature in Celsius.
 
-      iex> AHT20.Calc.celsius_from_raw_temperature(410343)
+      iex> AHT20.Calc.temperature_c_from_raw(410343)
       28.26671600341797
   """
-  @spec celsius_from_raw_temperature(integer) :: float
-  def celsius_from_raw_temperature(raw_temperature), do: raw_temperature / 1_048_576.0 * 200.0 - 50.0
+  @spec temperature_c_from_raw(integer) :: float
+  def temperature_c_from_raw(raw_temperature), do: raw_temperature / 1_048_576.0 * 200.0 - 50.0
 
   @doc """
   Calculates the temperature in Fahrenheit.
 
-      iex> AHT20.Calc.fahrenheit_from_raw_temperature(410343)
+      iex> AHT20.Calc.temperature_f_from_raw(410343)
       82.88008880615234
   """
-  @spec fahrenheit_from_raw_temperature(integer) :: float
-  def fahrenheit_from_raw_temperature(raw_temperature) do
-    celsius_from_raw_temperature(raw_temperature) * 9.0 / 5.0 + 32.0
-  end
-
-  @doc """
-  Obtains the humidity value from the sensor output.
-
-      iex> AHT20.Calc.raw_humidity_from_sensor_output(<<28, 38, 154, 118, 66, 231, 118>>)
-      158119
-  """
-  @spec raw_humidity_from_sensor_output(<<_::56>>) :: integer()
-  def raw_humidity_from_sensor_output(<<_state, humidity::20, _temperature::20, _crc>>) do
-    humidity
-  end
-
-  @doc """
-  Obtains the temperature value from the sensor output.
-
-      iex> AHT20.Calc.raw_temperature_from_sensor_output(<<28, 38, 154, 118, 66, 231, 118>>)
-      410343
-  """
-  @spec raw_temperature_from_sensor_output(<<_::56>>) :: integer()
-  def raw_temperature_from_sensor_output(<<_state, _humidity::20, temperature::20, _crc>>) do
-    temperature
+  @spec temperature_f_from_raw(integer) :: float
+  def temperature_f_from_raw(raw_temperature) do
+    temperature_c_from_raw(raw_temperature) * 9.0 / 5.0 + 32.0
   end
 end

lib/aht20/measurement.ex

@@ -1,42 +1,31 @@
 defmodule AHT20.Measurement do
   @moduledoc """
   One sensor measurement report.
-  Only the raw temperature and raw humidity values are computed directly from the sensor.
-  All other values are derived.
   """
 
-  defstruct [:temperature_c, :temperature_f, :relative_humidity, :raw_humidity, :raw_temperature]
+  defstruct [:temperature_c, :temperature_f, :humidity_rh, :raw_humidity, :raw_temperature]
 
   @type t :: %__MODULE__{
           temperature_c: number,
           temperature_f: number,
-          relative_humidity: number,
-          raw_humidity: number,
-          raw_temperature: number
+          humidity_rh: number
         }
 
   @doc """
   Converts raw sensor output into human-readable format.
 
       iex> AHT20.Measurement.from_sensor_output(<<28, 38, 154, 118, 66, 231, 118>>)
       %AHT20.Measurement{
-        raw_humidity: 158119,
-        raw_temperature: 410343,
-        relative_humidity: 15.079402923583984,
+        humidity_rh: 15.079402923583984,
         temperature_c: 28.26671600341797,
         temperature_f: 82.88008880615234
       }
   """
-  def from_sensor_output(sensor_output) do
-    raw_humidity = AHT20.Calc.raw_humidity_from_sensor_output(sensor_output)
-    raw_temperature = AHT20.Calc.raw_temperature_from_sensor_output(sensor_output)
-
+  def from_sensor_output(<<_state, raw_humidity::20, raw_temperature::20, _crc>>) do
     __struct__(
-      relative_humidity: AHT20.Calc.relative_humidity(raw_humidity),
-      temperature_c: AHT20.Calc.celsius_from_raw_temperature(raw_temperature),
-      temperature_f: AHT20.Calc.fahrenheit_from_raw_temperature(raw_temperature),
-      raw_humidity: raw_humidity,
-      raw_temperature: raw_temperature
+      humidity_rh: AHT20.Calc.humidity_rh_from_raw(raw_humidity),
+      temperature_c: AHT20.Calc.temperature_c_from_raw(raw_temperature),
+      temperature_f: AHT20.Calc.temperature_f_from_raw(raw_temperature)
     )
   end
 end

test/aht20_test.exs

@@ -29,9 +29,7 @@ defmodule AHT20Test do
       assert {:ok, data} = AHT20.read_data(sensor)
 
       assert data == %AHT20.Measurement{
-               raw_humidity: 158_119,
-               raw_temperature: 410_343,
-               relative_humidity: 15.079402923583984,
+               humidity_rh: 15.079402923583984,
                temperature_c: 28.26671600341797,
                temperature_f: 82.88008880615234
              }
@@ -61,9 +59,7 @@ defmodule AHT20Test do
       assert {:ok, data} = AHT20.read_data(pid)
 
       assert data == %AHT20.Measurement{
-               raw_humidity: 158_119,
-               raw_temperature: 410_343,
-               relative_humidity: 15.079402923583984,
+               humidity_rh: 15.079402923583984,
                temperature_c: 28.26671600341797,
                temperature_f: 82.88008880615234
              }