Have you ever had an array that you only want to include unique elements?
In this example we’re combining
list_2, then removing duplicate entries using the
#uniq method before assigning to the
Another approach would be to not include duplicate elements all together using one of the array set operators: the union operator
The union operator combines the unique values of two sets. Here we’re using this set operator to generate the same result using two arrays.
The difference operator returns the difference between two sets. Just like the previous example, we’ll use arrays.
What’s on the left side of the difference operator is important. It takes elements on the left (in our case the elements in the array) and compares them to the elements on the right; and the elements that are different are returned.
So in the example above,
list_1 is on the left (
['a', 'b', 'c']) and
list_2 is on the right
['c', 'd', 'e'].
The elements in
list_1 that are different (not included in) from the elements in
list_2 are the ones that are returned
We could easily see what elements are in
list_2 that are not included in
list_1 by placing
list_2 on the left side of the difference operator.
The intersection operator returns the elements that are common in both sets. It’s easy to think of
difference as opposites.