# List intersection

Python, List · Nov 2, 2020

Returns a list of elements that exist in both lists.

- Create a
`set`

from`a`

and`b`

. - Use the built-in set operator
`&`

to only keep values contained in both sets, then transform the`set`

back into a`list`

.

```
def intersection(a, b):
_a, _b = set(a), set(b)
return list(_a & _b)
```

`intersection([1, 2, 3], [4, 3, 2]) # [2, 3]`