Elixir functions for parsing Mnist binary data - http://yann.lecun.com/exdb/mnist/

MnistDataReader.ex

defmodule MnistDataReader do

  def read_training_image_data(path) do
    {:ok, data} = File.read path
    parse_training_image_data data
  end

  def read_training_label_data(path) do
    {:ok, data} = File.read path
    parse_training_label_data data
  end

  defp parse_training_label_data(binary_label_data) do
    #Read only the first 100 labels for experimentation
    <<
      _magic_number :: size(32),
      _number_of_items :: size(32),
      labels :: binary-size(100),
      _remaining_binary :: binary
    >> = binary_label_data

    labels = :binary.bin_to_list labels
    labels
  end

  defp parse_training_image_data(binary_data) do
    <<
      _magic_number :: size(32),
      _number_of_images :: size(32),
      number_of_rows :: size(32),
      number_of_columns :: size(32),
      images_data :: binary
    >> = binary_data
    
    #Read only the first 100 images for experimentation
    image_size = number_of_rows*number_of_columns
    image_binary_size = image_size*100
    <<
      images_data :: binary-size(image_binary_size),
      _remaining_binary :: binary
    >> = images_data
    raw_images_list = :binary.bin_to_list images_data
    images = Enum.chunk(raw_images_list, (number_of_rows*number_of_columns))
    images
  end

end