What’s new in 1.3.4 (October 17, 2021)

These are the changes in pandas 1.3.4. See Release notes for a full changelog including other versions of pandas.

Fixed regressions

• Fixed regression in DataFrame.convert_dtypes() incorrectly converts byte strings to strings (GH43183)

• Fixed regression in GroupBy.agg() where it was failing silently with mixed data types along axis=1 and MultiIndex (GH43209)

• Fixed regression in merge() with integer and NaN keys failing with outer merge (GH43550)

• Fixed regression in DataFrame.corr() raising ValueError with method="spearman" on 32-bit platforms (GH43588)

• Fixed performance regression in MultiIndex.equals() (GH43549)

• Fixed performance regression in GroupBy.first() and GroupBy.last() with StringDtype (GH41596)

• Fixed regression in Series.cat.reorder_categories() failing to update the categories on the Series (GH43232)

• Fixed regression in Series.cat.categories() setter failing to update the categories on the Series (GH43334)

• Fixed regression in read_csv() raising UnicodeDecodeError exception when memory_map=True (GH43540)

• Fixed regression in DataFrame.explode() raising AssertionError when column is any scalar which is not a string (GH43314)

• Fixed regression in Series.aggregate() attempting to pass args and kwargs multiple times to the user supplied func in certain cases (GH43357)

• Fixed regression when iterating over a DataFrame.groupby.rolling object causing the resulting DataFrames to have an incorrect index if the input groupings were not sorted (GH43386)

• Fixed regression in DataFrame.groupby.rolling.cov() and DataFrame.groupby.rolling.corr() computing incorrect results if the input groupings were not sorted (GH43386)

Bug fixes

• Fixed bug in pandas.DataFrame.groupby.rolling() and pandas.api.indexers.FixedForwardWindowIndexer leading to segfaults and window endpoints being mixed across groups (GH43267)

• Fixed bug in GroupBy.mean() with datetimelike values including NaT values returning incorrect results (GH43132)

• Fixed bug in Series.aggregate() not passing the first args to the user supplied func in certain cases (GH43357)

• Fixed memory leaks in Series.rolling.quantile() and Series.rolling.median() (GH43339)

Other

• The minimum version of Cython needed to compile pandas is now 0.29.24 (GH43729)

Contributors

A total of 17 people contributed patches to this release. People with a “+” by their names contributed a patch for the first time.

• Alexey Györi +

• DSM

• Irv Lustig

• Jeff Reback

• Julien de la Bruère-T +

• Matthew Zeitlin

• MeeseeksMachine

• Pandas Development Team

• Patrick Hoefler

• Richard Shadrach

• Shoham Debnath

• Simon Hawkins

• Thomas Li

• aptalca +

• jbrockmendel

• michal-gh +

• realead