Joao P Dubas
06b35cbceb
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This implementation should be made generic for all other scores.
72 lines
1.7 KiB
Elixir
72 lines
1.7 KiB
Elixir
defmodule Growth.Score.BMI do
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@moduledoc """
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Calculate z-score for body mass index for age.
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"""
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alias Growth.Calc.Centile
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alias Growth.Calc.ZScore
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@spec result(Growth.t()) :: Growth.t()
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@doc """
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Calculate z-score and centile values and add them to the growth measurement results.
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"""
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def result(%Growth{bmi: nil} = measure) do
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measure
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end
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def result(%Growth{results: results} = measure) do
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result =
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measure
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|> lms()
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|> Enum.map(fn {precision, {l, m, s}} ->
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{precision, {z_score(measure.bmi, l, m, s), centile(measure.bmi, l, m, s)}}
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end)
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%{measure | results: [%{bmi: result} | results]}
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end
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@spec lms(Growth.t()) :: [{String.t(), {number(), number(), number()}}]
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@doc """
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Get the fitted values of Box-Cox:
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* power (`l`)
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* median (`m`)
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* coefficient of variation (`s`)
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"""
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def lms(%Growth{} = measure) do
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[
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{measure.gender, "day", measure.age_in_days},
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{measure.gender, "week", measure.age_in_weeks},
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{measure.gender, "month", measure.age_in_months}
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]
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|> Enum.map(fn {_, precision, _} = key ->
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case :ets.lookup(__MODULE__, key) do
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[{^key, %{l: l, m: m, s: s}} | _] ->
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{precision, {l, m, s}}
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_ ->
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nil
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end
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end)
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|> Enum.reject(&is_nil/1)
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end
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@spec z_score(number(), number(), number(), number()) :: number()
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@doc """
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Check `Growth.Calc.ZScore.compute/4`.
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"""
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def z_score(value, l, m, s) do
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ZScore.compute(value, l, m, s)
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end
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@spec centile(number(), number(), number(), number()) :: number() | :na
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@doc """
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Check `Growth.Calc.Centile.compute/4`.
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"""
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def centile(value, l, m, s) do
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Centile.compute(value, l, m, s)
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end
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end
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