Check if an array is subset of another array in Ruby

Question

How can I check whether one array is a subset of another array, regardless of the order of elements?

a1 = [3, 6, 4]
a2 = [1, 2, 3, 4, 5, 6, 7, 8, 9]

...?

a         


        

Answer 1

Easiest may be:

(a1 - a2).empty?