Split a Ruby array into N equally-sized parts.

To split a Ruby array into n equally-sized parts:

a.each_slice( (a.size/n.to_f).round ).to_a

For example:

a = [1,2,3,4,5]; n = 3                     # => 3
a.each_slice( (a.size/n.to_f).round ).to_a # => [[1, 2], [3, 4], [5]]