STYLE: fix pylint unnecessary-comprehension warnings #49674
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Moisan
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Nov 12, 2022
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| # calling `dict` on a DataFrameGroupBy leads to a TypeError, | ||
| # we need to use a dictionary comprehension here | ||
| groups = { | ||
| key: gp for key, gp in grouped | ||
| } # pylint: disable=unnecessary-comprehension |
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Related question: is it intentional that dict(df.groupby(["k1", "k2"])) leads to a TypeError while it's possible to iterate on it as if it was a dictionary?
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Not exactly intentional, but I don't think there is a good way to make it work. The dict constructor either takes a mapping or an iterable. A groupby object has all the data for a mapping, but doesn't support accessing like a map. We can however use the fact that dict takes an iterable - you should be able to use dict(grouped.items()).
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dict(grouped.items()) leads to
AttributeError: 'DataFrameGroupBy' object has no attribute 'items'
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Ah, indeed! A couple of issues with my previous comment.
- GroupBy implements
__getitem__, so as far as Python is concerned it is a mapping; however our implementation of this method is not in the sense of a mapping (it is for column selection) - GroupBy implements
keysas a property; Python'sdictconstruction is expectingkeysto be a method. So when Python's dict constructor doesgrouped.keys(), it fails. dict(iter(grouped))works.
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* STYLE: fix pylint unnecessary-comprehension warnings * fixup! STYLE: fix pylint unnecessary-comprehension warnings * fixup! fixup! STYLE: fix pylint unnecessary-comprehension warnings
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Related to #48855
doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.