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ERR: clarify PerformanceWarning for fragmented frame #42942

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Merged
merged 3 commits into from
Aug 9, 2021
Merged

ERR: clarify PerformanceWarning for fragmented frame #42942

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f1664e4
ERR: clarify PerformanceWarning for fragmented frame
mzeitlin11 Aug 9, 2021
f161c4d
Fix spacing
mzeitlin11 Aug 9, 2021
d5b67ce
Remove whatsnew note
mzeitlin11 Aug 9, 2021
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v1.3.2.rst
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Expand Up @@ -45,6 +45,7 @@ Bug fixes
Other
~~~~~
- :meth:`pandas.read_parquet` now supports reading nullable dtypes with ``fastparquet`` versions above 0.7.1.
- Clarified suggested fix for ``PerformanceWarning`` emitted with a highly fragmented :class:`DataFrame` (:issue:`42579`)
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the release note above this one is not yet on 1.3.x (not backported), so this may need a manual backport.

Alternatively, I think we don't normally add a release note when just a message is changed.

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Ok sounds good, have just removed note then

-

.. ---------------------------------------------------------------------------
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4 changes: 2 additions & 2 deletions pandas/core/internals/managers.py
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Expand Up @@ -1178,8 +1178,8 @@ def insert(self, loc: int, item: Hashable, value: ArrayLike) -> None:
warnings.warn(
"DataFrame is highly fragmented. This is usually the result "
"of calling `frame.insert` many times, which has poor performance. "
"Consider using pd.concat instead. To get a de-fragmented frame, "
"use `newframe = frame.copy()`",
"Consider joining all columns at once using pd.concat(axis=1) "
"instead. To get a de-fragmented frame, use `newframe = frame.copy()`",
PerformanceWarning,
stacklevel=5,
)
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