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Add operator.is_none() #115808
Description
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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Activity
pythongh-115808: Add is_none operator
rhettinger commentedon Feb 22, 2024
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 commentedon Feb 22, 2024
Agreed -- I was going to suggest this. It also fits the general pattern of the
operatormodule: we have bothis_andis_not, bothtruthandnot_, etc.pythongh-115808: Add is_none operator
gh-115808: Add ``is_none`` and ``is_not_none`` to ``operator`` (#115814)
pythongh-115808: Add ``is_none`` and ``is_not_none`` to ``operator`` (p…