Python – Are there any built-in lambda for is notNone in python

I’ve seen the following idiom repeated a few times in python X = filter(lambda x: x is not none, X)).

I wish there was a built-in function in python for is not none (in its standard library or something like java’s apache-commons).

In my code, I organize it as

def isNotNone(X: Any) -> bool:
    return True if X is not None else False

X = filter(isNotNone, X)

You can use None.__ne__, which is the inequality check of None:

>>> lst = [0, [], None, ""]
>>> list(filter(None.__ne__, lst))
[0, [], '']

Technically, this doesn’t test x is not None but x != None, and may produce different results in some cases, such as for classes that compare equal to None, but it should work for most real-world cases.

As noted in the review, this is not the same for all versions of Python – or even defined – some correctly return True or False and others produce NotImplemented for most values, which is also coincidentally “valid” but should not be relied upon. Instead, it might be a better idea to define your own def or lambda or, for this use case, use list understanding.