Native Python function to remove NoneType elements from list?

Question

I\'m using Beautiful Soup in Python to scrape some data from HTML files. In some cases, Beautiful Soup returns lists that contain both string and NoneType

Answer 1

I think the cleanest way to do this would be:

#lis = some list with NoneType's
filter(None, lis)

Answer 2

You could easily remove all NoneType objects from a list using a list comprehension:

lis = [i for i in lis if i is not None]

Answer 3

You can do this using list comprehension:

clean = [x for x in lis if x != None]

As pointed in the comments you could also use is not, even if it essentially compiles to the same bytecode:

clean = [x for x in lis if x is not None]

You could also used filter (note: this will also filter empty strings, if you want more control over what you filter you can pass a function instead of None):

clean = filter(None, lis)

There is always the itertools approach if you want more efficient looping, but these basic approaches should work for most day to day cases.

Answer 4

List comprehension, as other answers proposed or, for the sake of completeness:

clean = filter(lambda x: x is not None, lis)

If the list is huge, an iterator approach is superior:

from itertools import ifilter
clean = ifilter(lambda x: x is not None, lis)

Answer 5

For those who came here from Google

In Python3 you can implement this using .__ne__ dunder method (or 'magic method' if you will):

>>> list1 = [0, 'foo', '', 512, None, 0, 'bar']
>>> list(filter(None.__ne__, list1))
[0, 'foo', '', 512, 0, 'bar']

This is how it works:

• None.__ne__(None) --> False

• None.__ne__(anything) --> NotImplemented

NotImplemented exeption effectively is True, e.g.:

>>> bool(None.__ne__('Something'))
True

As of the beginning of 2019, Python has no built-in function for filtering None values which avoids common pitfals with deleting zeroes, empty strings, etc.