8000 Add operator.is_none() · Issue #115808 · python/cpython · GitHub
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rhettinger opened this issue Feb 22, 2024 · 2 comments · Fixed by #115814
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Add operator.is_none() #115808

rhettinger opened this issue Feb 22, 2024 · 2 comments · Fixed by #115814
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type-feature A feature request or enhancement

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@rhettinger
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rhettinger commented Feb 22, 2024 •
edited by bedevere-app bot
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Feature or enhancement

Proposal:

With floating point data, the float('NaN') special value is commonly used as a placeholder for missing values. We provide math.isnan to support stripping out those values prior to sorting or summation:

>>> from math import isnan
>>> from itertools import filterfalse
>>> data = [3.3, float('nan'), 1.1, 2.2]
>>> sorted(filterfalse(isnan, data))
[1.1, 2.2, 3.3]

For non-float data, the None special value is commonly used as a placeholder for missing values. I propose a new function in the operator module analogous to math.isnan():

>>> data = ['c', None, 'a', 'b']
>>> sorted(filterfalse(is_none, data))
['a', 'b', 'c']

This helps fulfill a primary use case for the operator module which is to support functional programming with map(), filter(), etc.

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

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@rhettinger rhettinger added the type-feature A feature request or enhancement label Feb 22, 2024
ThexXTURBOXx added a commit to ThexXTURBOXx/cpython that referenced this issue Feb 22, 2024
@ThexXTURBOXx
pythongh-115808: Add is_none operator
63b788b
@ThexXTURBOXx ThexXTURBOXx mentioned this issue Feb 22, 2024
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@rhettinger
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For convenience, it might also be nice to have is_not_none(). The matches what would be done in a typical list comprehension: cleaned = [x for x in data if x is not None]. Also, it would save the need to know about filterfalse() in itertools module which is less well known that builtin functions. A simple builtin filter() call will suffice: mean(filter(is_not_none, data)).

@AlexWaygood
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For convenience, it might also be nice to have is_not_none()

Agreed -- I was going to suggest this. It also fits the general pattern of the operator module: we have both is_ and is_not, both truth and not_, etc.

ThexXTURBOXx added a commit to ThexXTURBOXx/cpython that referenced this issue Mar 4, 2024
@ThexXTURBOXx
pythongh-115808: Add is_none operator
72ccb45
AA-Turner pushed a commit that referenced this issue Aug 10, 2024
@ThexXTURBOXx @Eclips4
gh-115808: Add is_none and is_not_none to operator (#115814)
5580f31 
Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
blhsing pushed a commit to blhsing/cpython that referenced this issue Aug 22, 2024
@ThexXTURBOXx @Eclips4 @blhsing
pythongh-115808: Add is_none and is_not_none to operator (p…
34f25eb 
…ython#115814)

Co-authored-by: Kirill Podoprigora <kirill.bast9@mail.ru>
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gh-115808: Add is_none and is_not_none operators ThexXTURBOXx/cpython
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