Split an array in to n approximately pieces.

split_array.rb

# Split an array in to n approximately equal pieces.
#
# Example usage:
#
#   ('a'..'f').to_a.split_in_to(3)  => [["a", "b"], ["c", "d"], ["e", "f"]]
#   (1..7).to_a.split_in_to(2) => [[1, 2, 3, 4], [5, 6, 7]]

class Array
  def split_into(pieces = 2)
    len = self.count
    f   = (len.to_f / pieces).ceil
    1.upto(pieces).reduce([]) {|xs, i| xs << self[f*(i - 1)..(f*i - 1)] }
  end
end

# Stand alone version
def split_into(array, pieces = 2)
  len = array.count
  f   = (len.to_f / pieces).ceil
  1.upto(pieces).reduce([]) {|xs, i| xs << array[f*(i - 1)..(f*i - 1)] }
end