Data commit

Task/CSV-data-manipulation/Elixir/csv-data-manipulation.elixir

@@ -0,0 +1,51 @@
+defmodule Csv do
+  defstruct header: "", data: "", separator: ","
+
+  def from_file(path) do
+    [header | data] = path
+    |> File.stream!
+    |> Enum.to_list
+    |> Enum.map(&String.trim/1)
+
+    %Csv{ header: header, data: data }
+  end
+
+  def sums_of_rows(csv) do
+    Enum.map(csv.data, fn (row) -> sum_of_row(row, csv.separator) end)
+  end
+
+  def sum_of_row(row, separator) do
+    row
+    |> String.split(separator)
+    |> Enum.map(&String.to_integer/1)
+    |> Enum.sum
+    |> to_string
+  end
+
+  def append_column(csv, column_header, column_data) do
+    header = append_to_row(csv.header, column_header, csv.separator)
+
+    data = [csv.data, column_data]
+    |> List.zip
+    |> Enum.map(fn ({ row, value }) ->
+      append_to_row(row, value, csv.separator)
+    end)
+
+    %Csv{ header: header, data: data }
+  end
+
+  def append_to_row(row, value, separator) do
+    row <> separator <> value
+  end
+
+  def to_file(csv, path) do
+    body = Enum.join([csv.header | csv.data], "\n")
+
+    File.write(path, body)
+  end
+end
+
+csv = Csv.from_file("in.csv")
+csv
+|> Csv.append_column("SUM", Csv.sums_of_rows(csv))
+|> Csv.to_file("out.csv")