Ruby monkey patching

array.rb

class Array
  # [1, 2, 3, 4, 5, 6, 7, 8].to_columns 1, 2, 3, 2 => [[1], [2, 3], [4, 5, 6], [7, 8]]
  def to_columns *column_counts
    return [] if self.empty?
    result, start_iterator, end_iterator = [], 0, 0
    column_counts.each do |column_count|
      end_iterator = start_iterator + column_count
      cut = self[start_iterator...end_iterator]
      result << cut unless cut.nil?
      start_iterator += column_count
    end
    result
  end
  
  # [1, 2, 3, 4, 5, 6, 7, 8, 9].to_columns_in_lines 3 => [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
  def to_columns_in_lines column_count
    return [] if self.empty?
    return self if column_count == 0
    result = Array.new(column_count) { [] }
    self.each_with_index { |item, index| result[index % column_count] << item }
    result
  end
end