#!/usr/bin/env ruby

require 'bundler/setup'
require 'mnist'

require 'optparse'

num_sample = nil

opt = OptionParser.new
opt.banner = "Usage: #{$0} [options] IMAGE_FILE LABEL_FILE"
opt.version = Mnist::VERSION
opt.separator ''
opt.separator 'Options:'
opt.on('-n', '--sample=N', Integer, 'The number of samples') {|v| num_sample = v }
opt.parse!(ARGV)

nrows, ncols, images = Mnist.load_images(ARGV[0])
labels = Mnist.load_labels(ARGV[1])

if images.length != labels.length
  raise "The lengths of images and labels are not same"
end

print "y"
(nrows*ncols).times do |i|
  print ",x#{i}"
end
print "\r\n"

indices = 0...labels.length
indices = [*indices].sample(num_sample) if num_sample

indices.each do |index|
  label = labels[index]
  print label

  image = images[index]
  pixels = image.unpack('C*')
  pixels.each do |pixel|
    print ",#{pixel}"
  end

  print "\r\n"
end