The intersection of two Python lists using Set

Set is unordered unique collection of objects.

We can use Set to find the intersection of two lists/tuples.

Suppose that we have two lists.

>>> x = [1, 2, 3, 4, 5]
>>> y = [2, 6, 7, 3]

To find the intersection of the two lists, first change both x and y to the Set type, then use the intersection method (&).

>>> set(x) & set(y)
{2, 3}

If we need the output in list type, apply the list command, to the output.

>>> list(set(x) & set(y))
[2, 3]

The intersection of two Python lists

Suppose that you have two lists, x and y. You can list out the items that are common to the two lists.

>>> x = [1,2,3,4,5]
>>> y = [2,6,7,3]
>>> [i for i in y if i in x]
[2, 3]

To see how many items found in the intersection.

>>> len([i for i in y if i in x])
2