Ruby 1.9.2 リファレンスマニュアル > ライブラリ一覧 > matrixライブラリ > Matrixクラス > each_with_index

instance method Matrix#each_with_index

each_with_index {|e, row, col| ... } -> self

Yields all elements of the matrix, starting with those of the first row, along with the row index and column index, or returns an Enumerator is no block given

Matrix[ [1,2], [3,4] ].each_with_index do |e, row, col|
  puts "#{e} at #{row}, #{col}"
end
  # => 1 at 0, 0
  # => 2 at 0, 1
  # => 3 at 1, 0
  # => 4 at 1, 1