I am trying to compare two Ruby arrays to verify that all of the first array's elements are included in the second one. (The reverse isn't needed.)
For example:
a = ["hello", "goodbye"]
b = ["hello", "goodbye", "orange"]
This should return true.
However, I can't figure out a method that will allow me to do this. Any help would be appreciated!
Many ways are there to check the same :
a = ["hello", "goodbye"]
b = ["hello", "goodbye", "orange"]
(a - b).empty? # => true
a.all?{|i| b.include? i }
# => true
a = ["hello", "welcome"]
b = ["hello", "goodbye", "orange"]
(a - b).empty? # => false
a.all?{|i| b.include? i }
# => false
Array set logic is nice here:
a & b == a
a & b produces a new array consisting of the elements that exist in both a and b. You can then test it against a to make sure that the cross section contains all of the elements of a itself. See the manual entry on Array#& for more details.
a=[1,1,2]; b=[1,2,3]; p a&b==a #=> false since a&b == [1,2]. Per the duplicate question's answer, (a-b).empty? is perhaps a better bet.