Group continuos sequences in an array

group_sequence.rb

def group_sequence(seq)
  return [] if seq.size == 0
  g = Array.new
  sub = Array.new
  sub << seq[0]

  if seq.size > 2
    (seq[1..-1]).each do |s|
      if s -sub[-1] == 1
        sub << s
      else
        g << sub
        sub = Array.new
        sub << s
      end
    end
  end
  g << sub
end