nucleotide_count

elixir/nucleotide-count/lib/nucleotide_count.ex

@@ -0,0 +1,30 @@
+defmodule NucleotideCount do
+  @nucleotides [?A, ?C, ?G, ?T]
+
+  @doc """
+  Counts individual nucleotides in a DNA strand.
+
+  ## Examples
+
+  iex> NucleotideCount.count(~c"AATAA", ?A)
+  4
+
+  iex> NucleotideCount.count(~c"AATAA", ?T)
+  1
+  """
+  @spec count(charlist(), char()) :: non_neg_integer()
+  def count(strand, nucleotide), do: Enum.count(strand, &(&1 == nucleotide))
+
+  @doc """
+  Returns a summary of counts by nucleotide.
+
+  ## Examples
+
+  iex> NucleotideCount.histogram(~c"AATAA")
+  %{?A => 4, ?T => 1, ?C => 0, ?G => 0}
+  """
+  @spec histogram(charlist()) :: map()
+  def histogram(strand) do
+    for nucleotide <- @nucleotides, into: %{}, do: {nucleotide, count(strand, nucleotide)}
+  end
+end