DOC: clarify scalar vs list-like return types for .loc and []#65642
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closes pandas-dev#46593 Extend the indexing basics table with rows for the list-like ``DataFrame`` cases, and add a short note to the ``.loc`` docstring explaining that the *form* of the indexer (scalar vs. list-like) is what determines the return type, with the duplicate-labels exception called out. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
mroeschke
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May 15, 2026
| - A ``callable`` function with one argument (the calling Series or | ||
| DataFrame) and that returns valid output for indexing (one of the above) | ||
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| The *form* of the indexer, not the number of items it selects, |
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Could we show this as an example instead (note: I'm generally more fond of using Examples w/ doctest to ensure what we're describing doesn't go stale)
CloseChoice
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May 16, 2026
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Since I was mentioned in the PR description, I'll leave a review here. Take it for what you deem it's worth.
As mentioned by @mroeschke I would also appreciate an example + doctest. Otherwise this looks good and exactly what I had in mind when writing the referenced comment.
Per reviewer feedback (@mroeschke, @CloseChoice), swap the prose paragraph for a doctest-checked example pair contrasting ``df.loc[:, "max_speed"]`` (Series) with ``df.loc[:, ["max_speed"]]`` (DataFrame), so the documented behavior can't drift from reality. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
mroeschke
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Thanks @jbrockmendel |
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closes #46593
Summary
frame[[colname]]andframe[list_of_colnames](per @CloseChoice's suggestion in DOC: .loc improvement #46593)..locdocstring explaining that the form of the indexer (scalar vs. list-like) determines the return type, with the duplicate-labels exception spelled out.Test plan
pandas/core/indexing.py(9 passed)pre-commitclean on changed files