So I was looking for this in the ruby standard library and didn’t find it. So I rolled my own :) Enjoy!

class Array

  def rotate n=1 #positive right, negative left
    a = self.dup
    (n % self.size).times{ a = [ a.pop ] + a }
    a
  end

  def rotate! n=1
    replace rotate(n)
  end
end

   ...
    num.times{ a << a.shift }
   ...