v1.2.1.rst

What's new in 1.2.1 (January 18, 2021)

These are the changes in pandas 1.2.1. See :ref:`release` for a full changelog including other versions of pandas.

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Fixed regressions

• Fixed regression in :meth:`~DataFrame.to_csv` that created corrupted zip files when there were more rows than chunksize (:issue:`38714`)
• Fixed regression in :meth:`~DataFrame.to_csv` opening codecs.StreamReaderWriter in binary mode instead of in text mode (:issue:`39247`)
• Fixed regression in :meth:`read_csv` and other read functions were the encoding error policy (errors) did not default to "replace" when no encoding was specified (:issue:`38989`)
• Fixed regression in :func:`read_excel` with non-rawbyte file handles (:issue:`38788`)
• Fixed regression in :meth:`DataFrame.to_stata` not removing the created file when an error occured (:issue:`39202`)
• Fixed regression in DataFrame.__setitem__ raising ValueError when expanding :class:`DataFrame` and new column is from type "0 - name" (:issue:`39010`)
• Fixed regression in setting with :meth:`DataFrame.loc` raising ValueError when :class:`DataFrame` has unsorted :class:`MultiIndex` columns and indexer is a scalar (:issue:`38601`)
• Fixed regression in setting with :meth:`DataFrame.loc` raising KeyError with :class:`MultiIndex` and list-like columns indexer enlarging :class:`DataFrame` (:issue:`39147`)
• Fixed regression in :meth:`~DataFrame.groupby()` with :class:`Categorical` grouping column not showing unused categories for grouped.indices (:issue:`38642`)
• Fixed regression in :meth:`.GroupBy.sem` where the presence of non-numeric columns would cause an error instead of being dropped (:issue:`38774`)
• Fixed regression in :meth:`.DataFrameGroupBy.diff` raising for int8 and int16 columns (:issue:`39050`)
• Fixed regression in :meth:`DataFrame.groupby` when aggregating an ExtensionDType that could fail for non-numeric values (:issue:`38980`)
• Fixed regression in :meth:`.Rolling.skew` and :meth:`.Rolling.kurt` modifying the object inplace (:issue:`38908`)
• Fixed regression in :meth:`DataFrame.any` and :meth:`DataFrame.all` not returning a result for tz-aware datetime64 columns (:issue:`38723`)
• Fixed regression in :meth:`DataFrame.apply` with axis=1 using str accessor in apply function (:issue:`38979`)
• Fixed regression in :meth:`DataFrame.replace` raising ValueError when :class:`DataFrame` has dtype bytes (:issue:`38900`)
• Fixed regression in :meth:`Series.fillna` that raised RecursionError with datetime64[ns, UTC] dtype (:issue:`38851`)
• Fixed regression in comparisons between NaT and datetime.date objects incorrectly returning True (:issue:`39151`)
• Fixed regression in calling NumPy :func:`~numpy.ufunc.accumulate` ufuncs on DataFrames, e.g. np.maximum.accumulate(df) (:issue:`39259`)
• Fixed regression in repr of float-like strings of an object dtype having trailing 0's truncated after the decimal (:issue:`38708`)
• Fixed regression that raised AttributeError with PyArrow versions [0.16.0, 1.0.0) (:issue:`38801`)
• Fixed regression in :func:`pandas.testing.assert_frame_equal` raising TypeError with check_like=True when :class:`Index` or columns have mixed dtype (:issue:`39168`)

We have reverted a commit that resulted in several plotting related regressions in pandas 1.2.0 (:issue:`38969`, :issue:`38736`, :issue:`38865`, :issue:`38947` and :issue:`39126`). As a result, bugs reported as fixed in pandas 1.2.0 related to inconsistent tick labeling in bar plots are again present (:issue:`26186` and :issue:`11465`)

Bug fixes

• Bug in :meth:`read_csv` with float_precision="high" caused segfault or wrong parsing of long exponent strings. This resulted in a regression in some cases as the default for float_precision was changed in pandas 1.2.0 (:issue:`38753`)
• Bug in :func:`read_csv` not closing an opened file handle when a csv.Error or UnicodeDecodeError occurred while initializing (:issue:`39024`)
• Bug in :func:`pandas.testing.assert_index_equal` raising TypeError with check_order=False when :class:`Index` has mixed dtype (:issue:`39168`)

Other

• The deprecated attributes _AXIS_NAMES and _AXIS_NUMBERS of :class:`DataFrame` and :class:`Series` will no longer show up in dir or inspect.getmembers calls (:issue:`38740`)
• Bumped minimum fastparquet version to 0.4.0 to avoid AttributeError from numba (:issue:`38344`)
• Bumped minimum pymysql version to 0.8.1 to avoid test failures (:issue:`38344`)
• Fixed build failure on MacOS 11 in Python 3.9.1 (:issue:`38766`)
• Added reference to backwards incompatible check_freq arg of :func:`testing.assert_frame_equal` and :func:`testing.assert_series_equal` in :ref:`pandas 1.1.0 whats new <whatsnew_110.api_breaking.testing.check_freq>` (:issue:`34050`)

Contributors

.. contributors:: v1.2.0..v1.2.1|HEAD