Split array up into n-groups of m size? [duplicate]

Answer 1

Use Enumerable#each_slice.

a.each_slice(3).to_a

Or, to iterate (and not bother with keeping the array):

a.each_slice(3) do |x,y,z|
  p [x,y,z]
end

Answer 2

a = (1..6).to_a
a.each_slice(2).to_a # => [[1, 2], [3, 4], [5, 6]]
a.each_slice(3).to_a # => [[1, 2, 3], [4, 5, 6]]
a.each_slice(4).to_a # => [[1, 2, 3, 4], [5, 6]]