How to check if a value in one list is in another list with a one-liner for an if statement in Python if I'm not using sets?

Question

I\'m trying to construct a one liner that would check if any of the values in one list are present in another list and return True or False if it does or does not.

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Answer 1

You can us an any(..) builtin function with a generator expression:

any(e in list2 for e in list1)

So this will check if there is at least one element that occurs in both lists.

Note however that this will result in a worst-case O(n²) algorithm. If the elements are hashable for instance, and you can use a set, we can make it an O(n) average-case algorithm.