These are the changes in pandas 1.3.1. See :ref:`release` for a full changelog including other versions of pandas.
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- pandas could not be built on PyPy (:issue:`42355`)
- :class:`DataFrame` constructed with an older version of pandas could not be unpickled (:issue:`42345`)
- Performance regression in constructing a :class:`DataFrame` from a dictionary of dictionaries (:issue:`42248`)
- Fixed regression in :meth:`DataFrame.agg` dropping values when the DataFrame had an Extension Array dtype, a duplicate index, and
axis=1(:issue:`42380`) - Fixed regression in :meth:`DataFrame.astype` changing the order of noncontiguous data (:issue:`42396`)
- Performance regression in :class:`DataFrame` in reduction operations requiring casting such as :meth:`DataFrame.mean` on integer data (:issue:`38592`)
- Performance regression in :meth:`DataFrame.to_dict` and :meth:`Series.to_dict` when
orientargument one of "records", "dict", or "split" (:issue:`42352`) - Fixed regression in indexing with a
listsubclass incorrectly raisingTypeError(:issue:`42433`, :issue:`42461`) - Fixed regression in :meth:`DataFrame.isin` and :meth:`Series.isin` raising
TypeErrorwith nullable data containing at least one missing value (:issue:`42405`) - Regression in :func:`concat` between objects with bool dtype and integer dtype casting to object instead of to integer (:issue:`42092`)
- Bug in :class:`Series` constructor not accepting a
dask.Array(:issue:`38645`) - Fixed regression for
SettingWithCopyWarningdisplaying incorrect stacklevel (:issue:`42570`) - Fixed regression for :func:`merge_asof` raising
KeyErrorwhen one of thebycolumns is in the index (:issue:`34488`) - Fixed regression in :func:`to_datetime` returning pd.NaT for inputs that produce duplicated values, when
cache=True(:issue:`42259`) - Fixed regression in :meth:`SeriesGroupBy.value_counts` that resulted in an
IndexErrorwhen called on a Series with one row (:issue:`42618`)
- Fixed bug in :meth:`DataFrame.transpose` dropping values when the DataFrame had an Extension Array dtype and a duplicate index (:issue:`42380`)
- Fixed bug in :meth:`DataFrame.to_xml` raising
KeyErrorwhen called withindex=Falseand an offset index (:issue:`42458`) - Fixed bug in :meth:`.Styler.set_sticky` not handling index names correctly for single index columns case (:issue:`42537`)
- Fixed bug in :meth:`DataFrame.copy` failing to consolidate blocks in the result (:issue:`42579`)
.. contributors:: v1.3.0..v1.3.1