Data commit

Task/Permutation-test/Elixir/permutation-test.elixir

@@ -0,0 +1,28 @@
+defmodule Permutation do
+  def statistic(ab, a) do
+    sumab = Enum.sum(ab)
+    suma  = Enum.sum(a)
+    suma / length(a) - (sumab - suma) / (length(ab) - length(a))
+  end
+
+  def test(a, b) do
+    ab = a ++ b
+    tobs = statistic(ab, a)
+    {under, count} = Enum.reduce(comb(ab, length(a)), {0,0}, fn perm, {under, count} ->
+      if statistic(ab, perm) <= tobs, do: {under+1, count+1},
+                                    else: {under  , count+1}
+    end)
+    under * 100.0 / count
+  end
+
+  defp comb(_, 0), do: [[]]
+  defp comb([], _), do: []
+  defp comb([h|t], m) do
+    (for l <- comb(t, m-1), do: [h|l]) ++ comb(t, m)
+  end
+end
+
+treatmentGroup = [85, 88, 75, 66, 25, 29, 83, 39, 97]
+controlGroup   = [68, 41, 10, 49, 16, 65, 32, 92, 28, 98]
+under = Permutation.test(treatmentGroup, controlGroup)
+:io.fwrite "under = ~.2f%, over = ~.2f%~n", [under, 100-under]