The Ruby Enumerable#zip method (matrix transform), in Ruby

zip.rb

require 'minitest/autorun'

class Array
  def zzzip(*args)
    results = []
    i = 0
    each do |ary_element|  
      zipped_entry = args.inject([ary_element]) do |memo, element| 
        memo << element[i] 
      end

      results << zipped_entry
      i += 1
    end
    results
  end
end

class TestZzzip < MiniTest::Unit::TestCase
  def setup
    @a = ['Low', 'Medium', 'High']
    @b = [{'a' => 1}, {'b' => 2}, {'c' => 3}]
  end

  def test_zipping_no_args 
    assert_equal @a.zip, @a.zzzip
  end

  def test_zipping_equal_number_of_args
    assert_equal @a.zip([7,8,9]), @a.zzzip([7,8,9])
  end

  def test_zipping_more_exotic_arrays
    assert_equal @a.zip(@b), @a.zzzip(@b)
  end
end