princelab/mspire

class Array
  # copied from ActiveSupport CoreExtensions
  def in_groups(number, fill_with = nil)
    # size / number gives minor group size;
    # size % number gives how many objects need extra accomodation;
    # each group hold either division or division + 1 items.
    division = size / number
    modulo = size % number

    # create a new array avoiding dup
    groups = []
    start = 0

    number.times do |index|
      length = division + (modulo > 0 && modulo > index ? 1 : 0)
      padding = fill_with != false &&
        modulo > 0 && length == division ? 1 : 0
      groups << slice(start, length).concat([fill_with] * padding)
      start += length
    end

    if block_given?
      groups.each{|g| yield(g) }
    else
      groups
    end
  end
end