BUG: `KeyError` in `Series.getitem` with datetime index and mixed unit slice in pandas 3.0.0rc0 (original) (raw)

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Reproducible Example

This script succeeded in pandas 2.x, but raises a KeyError in pandas 3.0.0rc0:

import pandas as pd

df = pd.Series(1, index=pd.date_range(start="2000-01-01", freq="h", periods=8)) start = pd.Timestamp("2000-01-01 01:00:00") # unit=us stop = start + pd.Timedelta(1) # unit=ns df.loc[start:stop]

The mix of us-resolution datetime index with a ns-resolution slice seems relevant. Casting stop to us resolution with stop = (start + pd.Timedelta(1)).as_unit("us") avoids the error.

Issue Description

uv run --python=3.13 --with pandas==3.0.0rc0 python bug.py

fails with

Traceback (most recent call last): File "/Users/toaugspurger/gh/bug.py", line 6, in df.loc[start:stop] ~~~~~~^^^^^^^^^^^^ File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexing.py", line 1207, in getitem return self._getitem_axis(maybe_callable, axis=axis) ~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexing.py", line 1429, in _getitem_axis return self._get_slice_axis(key, axis=axis) ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^ File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexing.py", line 1461, in _get_slice_axis indexer = labels.slice_indexer(slice_obj.start, slice_obj.stop, slice_obj.step) File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/datetimes.py", line 1061, in slice_indexer return Index.slice_indexer(self, start, end, step) ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^ File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/base.py", line 6690, in slice_indexer start_slice, end_slice = self.slice_locs(start, end, step=step) ~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^ File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/base.py", line 6952, in slice_locs end_slice = self.get_slice_bound(end, "right") File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/base.py", line 6860, in get_slice_bound raise err from None File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/base.py", line 6854, in get_slice_bound slc = self.get_loc(label) File "/Users/toaugspurger/.cache/uv/archive-v0/GlcV9lNBXMPGHt8xIqa_B/lib/python3.13/site-packages/pandas/core/indexes/datetimes.py", line 987, in get_loc raise KeyError(orig_key) from err KeyError: Timestamp('2000-01-01 01:00:00.000000001')

Expected Behavior

Return the matching rows:

2000-01-01 01:00:00    1
Freq: h, dtype: int64

Installed Versions