Find if any element of list exists in another list in Python

Question

The question is about a quicker, ie. more pythonic, way to test if any of the elements in an iterable exists inside another iterable.

What I am trying to do is something like:

if "foo" in terms or "bar" in terms or "baz" in terms: pass

But apparently this way repeats the 'in terms' clause and bloats the code, especially when we are dealing with many more elements. So I wondered whether is a better way to do this in python.

possible duplicate of [Python Check if one of the following items is in a list](http://stackoverflow.com/questions/740287/python-check-if-one-of-the-following-items-is-in-a-list) — Eric, Mar 20 '14 at 12:34

score 5 · Answer 1 · answered Mar 20 '14 at 11:26

5

You could also consider in your special case if it is possible to use sets instead of iterables. If both (foobarbaz and terms) are sets, then you can just write

if foobarbaz & terms:
    pass

This isn't particularly faster than your way, but it is smaller code by far and thus probably better for reading.

And of course, not all iterables can be converted to sets, so it depends on your usecase.

answered Mar 20 '14 at 11:26

Alfe

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Interestingly enough, it applies to my use case. I should have used sets from the beginning. Thanks! – Thanasis Papoutsidakis Mar 20 '14 at 11:34

score 4 · Answer 2 · answered Mar 20 '14 at 11:19

4

Figured out a way, posting here for easy reference. Try this:

if any(term in terms for term in ("foo", "bar", "baz")): pass

answered Mar 20 '14 at 11:19

Thanasis Papoutsidakis

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score 3 · Answer 3 · answered Mar 20 '14 at 12:32

3

Faster than Alfe's answer, since it only tests for, rather than calculates the, intersection

if not set(terms).isdisjoint({'foo', 'bar', 'baz'}):
    pass

answered Mar 20 '14 at 12:32

Eric

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Find if any element of list exists in another list in Python

3 Answers3