DOC: clarify loc slice step behavior with example closes #63311 #63346
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When using .loc[start:stop:step], start/stop use label semantics but step is positional within that range. Added example showing difference from explicit label selection. Closes pandas-dev#63311
mroeschke
reviewed
Dec 12, 2025
doc/source/user_guide/indexing.rst
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| .. ipython:: python | ||
| s = pd.Series(range(10), index=[0, 5, 10, 15, 20, 25, 30, 35, 40, 45]) | ||
| s.loc[10:50:5] # (10), then skip 3 positions → 35 only |
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Could you also show a similar example where the index is not numeric?
rhshadrach
requested changes
Dec 12, 2025
doc/source/user_guide/indexing.rst
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| For more information about duplicate labels, see | ||
| :ref:`Duplicate Labels <duplicates>`. | ||
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| Also, when using a slice with a step, such as ``.loc[start:stop:step]``, note that |
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The previous paragraph also starts with Also,, just from a prose standpoint I think we should avoid this.
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| Also, when using a slice with a step, such as ``.loc[start:stop:step]``, note that | |
| When using a slice with a step, such as ``.loc[start:stop:step]``, note that |
doc/source/user_guide/indexing.rst
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| the **positional index** within that label range. This means a stepped slice | ||
| may return different labels than selecting an explicit list, even when they | ||
| appear similar. |
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I think this could be made a little more specific.
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| the **positional index** within that label range. This means a stepped slice | |
| may return different labels than selecting an explicit list, even when they | |
| appear similar. | |
| the **positional index** within that label range. This means a stepped slice | |
| will behave differently than using the labels `range(start, stop, step)` when | |
| the index is not contiguous integers. |
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Updated per feedback:
The string index example clarifies that step is positional regardless of whether you use integers, characters, or other index types. Pre-commit checks passed ✓ Happy to help, if any further updates are needed :) |
rhshadrach
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When using .loc[start:stop:step], start/stop use label semantics but step is positional within that range. Added example showing difference from explicit label selection.
Closes #63311
stepwith slice for label-based indexing #63311doc/source/whatsnew/vX.X.X.rstfile if fixing a bug or adding a new feature.AGENTS.md.