BUG: get_indexer rountripping through string dtype #56013
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mroeschke
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Strings
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This pull request is stale because it has been open for thirty days with no activity. Please update and respond to this comment if you're still interested in working on this. |
pandas/core/indexes/base.py
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| @@ -6591,6 +6591,9 @@ def _maybe_cast_listlike_indexer(self, target) -> Index: | |||
| """ | |||
| Analogue to maybe_cast_indexer for get_indexer instead of get_loc. | |||
| """ | |||
| if not hasattr(target, "dtype") and self.dtype == object: | |||
| # Avoid inference for object since we are casting back later anyway | |||
| return Index(target, dtype=self.dtype) | |||
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hmm this might prevent us from doing intentional inference in _maybe_downcast_for_indexing
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@jbrockmendel could you think of a concrete situation where this might happen?
(the tests are all passing, so don't seem to cover that?)
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Looking at _maybe_downcast_for_indexing more closely, we are downcasting object dtype index to the other dtype, because this can give a performance improvement, right?
This might actually also be true for object/string combo, but I think correctness if more important, and if missing values are handled differently by downcasting, we should avoid that for now for this combo, until we can solve that better.
I will just make the check a bit more specific for object dtype then (even more ugly, but at least fixing this issue)
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Looks like this has gone stale and needs a rebase. Closing to clear the queue but feel free to reopen when you have time |
…ough string dtype) (#60339) Backport PR #56013: BUG: get_indexer rountripping through string dtype Co-authored-by: Patrick Hoefler <[email protected]>
doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.cc @jbrockmendel this feels a bit special casy, thoughts?