Log Message:
py-pandas: updated to 1.2.4

What's new in 1.2.4 (April 12, 2021)

Fixed regressions
- Fixed regression in :meth:`DataFrame.sum` when ``min_count`` greater than the \ 
:class:`DataFrame` shape was passed resulted in a ``ValueError`` \ 
(:issue:`39738`)
- Fixed regression in :meth:`DataFrame.to_json` raising ``AttributeError`` when \ 
run on PyPy (:issue:`39837`)
- Fixed regression in (in)equality comparison of ``pd.NaT`` with a \ 
non-datetimelike numpy array returning a scalar instead of an array \ 
(:issue:`40722`)
- Fixed regression in :meth:`DataFrame.where` not returning a copy in the case \ 
of an all True condition (:issue:`39595`)
- Fixed regression in :meth:`DataFrame.replace` raising ``IndexError`` when \ 
``regex`` was a multi-key dictionary (:issue:`39338`)
- Fixed regression in repr of floats in an ``object`` column not respecting \ 
``float_format`` when printed in the console or outputted through \ 
:meth:`DataFrame.to_string`, :meth:`DataFrame.to_html`, and \ 
:meth:`DataFrame.to_latex` (:issue:`40024`)
- Fixed regression in NumPy ufuncs such as ``np.add`` not passing through all \ 
arguments for :class:`DataFrame`

What's new in 1.2.3 (March 02, 2021)

Fixed regressions
- Fixed regression in :meth:`~DataFrame.to_excel` raising ``KeyError`` when \ 
giving duplicate columns with ``columns`` attribute (:issue:`39695`)
- Fixed regression in nullable integer unary ops propagating mask on assignment \ 
(:issue:`39943`)
- Fixed regression in :meth:`DataFrame.__setitem__` not aligning \ 
:class:`DataFrame` on right-hand side for boolean indexer (:issue:`39931`)
- Fixed regression in :meth:`~DataFrame.to_json` failing to use ``compression`` \ 
with URL-like paths that are internally opened in binary mode or with \ 
user-provided file objects that are opened in binary mode (:issue:`39985`)
- Fixed regression in :meth:`Series.sort_index` and \ 
:meth:`DataFrame.sort_index`, which exited with an ungraceful error when having \ 
kwarg ``ascending=None`` passed. Passing ``ascending=None`` is still considered \ 
invalid, and the improved error message suggests a proper usage (``ascending`` \ 
must be a boolean or a list-like of boolean) (:issue:`39434`)
- Fixed regression in :meth:`DataFrame.transform` and :meth:`Series.transform` \ 
giving incorrect column labels when passed a dictionary with a mix of list and \ 
non-list values (:issue:`40018`)

What's new in 1.2.2 (February 09, 2021)
---------------------------------------

These are the changes in pandas 1.2.2. See :ref:`release` for a full changelog
including other versions of pandas.

{{ header }}

.. ---------------------------------------------------------------------------

.. _whatsnew_122.regressions:

Fixed regressions
~~~~~~~~~~~~~~~~~

- Fixed regression in :func:`read_excel` that caused it to raise \ 
``AttributeError`` when checking version of older xlrd versions (:issue:`38955`)
- Fixed regression in :class:`DataFrame` constructor reordering element when \ 
construction from datetime ndarray with dtype not ``"datetime64[ns]"`` \ 
(:issue:`39422`)
- Fixed regression in :meth:`DataFrame.astype` and :meth:`Series.astype` not \ 
casting to bytes dtype (:issue:`39474`)
- Fixed regression in :meth:`~DataFrame.to_pickle` failing to create bz2/xz \ 
compressed pickle files with ``protocol=5`` (:issue:`39002`)
- Fixed regression in :func:`pandas.testing.assert_series_equal` and \ 
:func:`pandas.testing.assert_frame_equal` always raising ``AssertionError`` when \ 
comparing extension dtypes (:issue:`39410`)
- Fixed regression in :meth:`~DataFrame.to_csv` opening ``codecs.StreamWriter`` \ 
in binary mode instead of in text mode and ignoring user-provided ``mode`` \ 
(:issue:`39247`)
- Fixed regression in :meth:`Categorical.astype` casting to incorrect dtype when \ 
``np.int32`` is passed to dtype argument (:issue:`39402`)
- Fixed regression in :meth:`~DataFrame.to_excel` creating corrupt files when \ 
appending (``mode="a"``) to an existing file (:issue:`39576`)
- Fixed regression in :meth:`DataFrame.transform` failing in case of an empty \ 
DataFrame or Series (:issue:`39636`)
- Fixed regression in :meth:`~DataFrame.groupby` or :meth:`~DataFrame.resample` \ 
when aggregating an all-NaN or numeric object dtype column (:issue:`39329`)
- Fixed regression in :meth:`.Rolling.count` where the ``min_periods`` argument \ 
would be set to ``0`` after the operation (:issue:`39554`)
- Fixed regression in :func:`read_excel` that incorrectly raised when the \ 
argument ``io`` was a non-path and non-buffer and the ``engine`` argument was \ 
specified (:issue:`39528`)

.. ---------------------------------------------------------------------------

.. _whatsnew_122.bug_fixes:

Bug fixes
~~~~~~~~~

- :func:`pandas.read_excel` error message when a specified ``sheetname`` does \ 
not exist is now uniform across engines (:issue:`39250`)
- Fixed bug in :func:`pandas.read_excel` producing incorrect results when the \ 
engine ``openpyxl`` is used and the excel file is missing or has incorrect \ 
dimension information; the fix requires ``openpyxl`` >= 3.0.0, prior versions \ 
may still fail (:issue:`38956`, :issue:`39001`)
- Fixed bug in :func:`pandas.read_excel` sometimes producing a ``DataFrame`` \ 
with trailing rows of ``np.nan`` when the engine ``openpyxl`` is used \ 
(:issue:`39181`)

What's new in 1.2.1 (January 20, 2021)
--------------------------------------

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

{{ header }}

.. ---------------------------------------------------------------------------

.. _whatsnew_121.regressions:

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`)

What's new in 1.2.0 (December 26, 2020)

Performance improvements
- Performance improvements when creating DataFrame or Series with dtype ``str`` \ 
or :class:`StringDtype` from array with many string elements (:issue:`36304`, \ 
:issue:`36317`, :issue:`36325`, :issue:`36432`, :issue:`37371`)
- Performance improvement in :meth:`.GroupBy.agg` with the ``numba`` engine \ 
(:issue:`35759`)
- Performance improvements when creating :meth:`Series.map` from a huge \ 
dictionary (:issue:`34717`)
- Performance improvement in :meth:`.GroupBy.transform` with the ``numba`` \ 
engine (:issue:`36240`)
- :class:`.Styler` uuid method altered to compress data transmission over web \ 
whilst maintaining reasonably low table collision probability (:issue:`36345`)
- Performance improvement in :func:`to_datetime` with non-ns time unit for \ 
``float`` ``dtype`` columns (:issue:`20445`)
- Performance improvement in setting values on an :class:`IntervalArray` \ 
(:issue:`36310`)
- The internal index method :meth:`~Index._shallow_copy` now makes the new index \ 
and original index share cached attributes, avoiding creating these again, if \ 
created on either. This can speed up operations that depend on creating copies \ 
of existing indexes (:issue:`36840`)
- Performance improvement in :meth:`.RollingGroupby.count` (:issue:`35625`)
- Small performance decrease to :meth:`.Rolling.min` and :meth:`.Rolling.max` \ 
for fixed windows (:issue:`36567`)
- Reduced peak memory usage in :meth:`DataFrame.to_pickle` when using \ 
``protocol=5`` in python 3.8+ (:issue:`34244`)
- Faster ``dir`` calls when the object has many index labels, e.g. ``dir(ser)`` \ 
(:issue:`37450`)
- Performance improvement in :class:`ExpandingGroupby` (:issue:`37064`)
- Performance improvement in :meth:`Series.astype` and :meth:`DataFrame.astype` \ 
for :class:`Categorical` (:issue:`8628`)
- Performance improvement in :meth:`DataFrame.groupby` for ``float`` ``dtype`` \ 
(:issue:`28303`), changes of the underlying hash-function can lead to changes in \ 
float based indexes sort ordering for ties (e.g. :meth:`Index.value_counts`)
- Performance improvement in :meth:`pd.isin` for inputs with more than 1e6 \ 
elements (:issue:`36611`)
- Performance improvement for :meth:`DataFrame.__setitem__` with list-like \ 
indexers (:issue:`37954`)
- :meth:`read_json` now avoids reading entire file into memory when chunksize is \ 
specified (:issue:`34548`)

Bug fixes

Categorical
- :meth:`Categorical.fillna` will always return a copy, validate a passed fill \ 
value regardless of whether there are any NAs to fill, and disallow an ``NaT`` \ 
as a fill value for numeric categories (:issue:`36530`)
- Bug in :meth:`Categorical.__setitem__` that incorrectly raised when trying to \ 
set a tuple value (:issue:`20439`)
- Bug in :meth:`CategoricalIndex.equals` incorrectly casting non-category \ 
entries to ``np.nan`` (:issue:`37667`)
- Bug in :meth:`CategoricalIndex.where` incorrectly setting non-category entries \ 
to ``np.nan`` instead of raising ``TypeError`` (:issue:`37977`)
- Bug in :meth:`Categorical.to_numpy` and ``np.array(categorical)`` with \ 
tz-aware ``datetime64`` categories incorrectly dropping the time zone \ 
information instead of casting to object dtype (:issue:`38136`)

Datetime-like
- Bug in :meth:`DataFrame.combine_first` that would convert datetime-like column \ 
on other :class:`DataFrame` to integer when the column is not present in \ 
original :class:`DataFrame` (:issue:`28481`)
- Bug in :attr:`.DatetimeArray.date` where a ``ValueError`` would be raised with \ 
a read-only backing array (:issue:`33530`)
- Bug in ``NaT`` comparisons failing to raise ``TypeError`` on invalid \ 
inequality comparisons (:issue:`35046`)
- Bug in :class:`.DateOffset` where attributes reconstructed from pickle files \ 
differ from original objects when input values exceed normal ranges (e.g. \ 
months=12) (:issue:`34511`)
- Bug in :meth:`.DatetimeIndex.get_slice_bound` where ``datetime.date`` objects \ 
were not accepted or naive :class:`Timestamp` with a tz-aware \ 
:class:`.DatetimeIndex` (:issue:`35690`)
- Bug in :meth:`.DatetimeIndex.slice_locs` where ``datetime.date`` objects were \ 
not accepted (:issue:`34077`)
- Bug in :meth:`.DatetimeIndex.searchsorted`, \ 
:meth:`.TimedeltaIndex.searchsorted`, :meth:`PeriodIndex.searchsorted`, and \ 
:meth:`Series.searchsorted` with ``datetime64``, ``timedelta64`` or \ 
:class:`Period` dtype placement of ``NaT`` values being inconsistent with NumPy \ 
(:issue:`36176`, :issue:`36254`)
- Inconsistency in :class:`.DatetimeArray`, :class:`.TimedeltaArray`, and \ 
:class:`.PeriodArray` method ``__setitem__`` casting arrays of strings to \ 
datetime-like scalars but not scalar strings (:issue:`36261`)
- Bug in :meth:`.DatetimeArray.take` incorrectly allowing ``fill_value`` with a \ 
mismatched time zone (:issue:`37356`)
- Bug in :class:`.DatetimeIndex.shift` incorrectly raising when shifting empty \ 
indexes (:issue:`14811`)
- :class:`Timestamp` and :class:`.DatetimeIndex` comparisons between tz-aware \ 
and tz-naive objects now follow the standard library ``datetime`` behavior, \ 
returning ``True``/``False`` for ``!=``/``==`` and raising for inequality \ 
comparisons (:issue:`28507`)
- Bug in :meth:`.DatetimeIndex.equals` and :meth:`.TimedeltaIndex.equals` \ 
incorrectly considering ``int64`` indexes as equal (:issue:`36744`)
- :meth:`Series.to_json`, :meth:`DataFrame.to_json`, and :meth:`read_json` now \ 
implement time zone parsing when orient structure is ``table`` (:issue:`35973`)
- :meth:`astype` now attempts to convert to ``datetime64[ns, tz]`` directly from \ 
``object`` with inferred time zone from string (:issue:`35973`)
- Bug in :meth:`.TimedeltaIndex.sum` and :meth:`Series.sum` with ``timedelta64`` \ 
dtype on an empty index or series returning ``NaT`` instead of ``Timedelta(0)`` \ 
(:issue:`31751`)
- Bug in :meth:`.DatetimeArray.shift` incorrectly allowing ``fill_value`` with a \ 
mismatched time zone (:issue:`37299`)
- Bug in adding a :class:`.BusinessDay` with nonzero ``offset`` to a non-scalar \ 
other (:issue:`37457`)
- Bug in :func:`to_datetime` with a read-only array incorrectly raising \ 
(:issue:`34857`)
- Bug in :meth:`Series.isin` with ``datetime64[ns]`` dtype and \ 
:meth:`.DatetimeIndex.isin` incorrectly casting integers to datetimes \ 
(:issue:`36621`)
- Bug in :meth:`Series.isin` with ``datetime64[ns]`` dtype and \ 
:meth:`.DatetimeIndex.isin` failing to consider tz-aware and tz-naive datetimes \ 
as always different (:issue:`35728`)
- Bug in :meth:`Series.isin` with ``PeriodDtype`` dtype and \ 
:meth:`PeriodIndex.isin` failing to consider arguments with different \ 
``PeriodDtype`` as always different (:issue:`37528`)
- Bug in :class:`Period` constructor now correctly handles nanoseconds in the \ 
``value`` argument (:issue:`34621` and :issue:`17053`)

Timedelta
- Bug in :class:`.TimedeltaIndex`, :class:`Series`, and :class:`DataFrame` \ 
floor-division with ``timedelta64`` dtypes and ``NaT`` in the denominator \ 
(:issue:`35529`)
- Bug in parsing of ISO 8601 durations in :class:`Timedelta` and \ 
:func:`to_datetime` (:issue:`29773`, :issue:`36204`)
- Bug in :func:`to_timedelta` with a read-only array incorrectly raising \ 
(:issue:`34857`)
- Bug in :class:`Timedelta` incorrectly truncating to sub-second portion of a \ 
string input when it has precision higher than nanoseconds (:issue:`36738`)

Timezones
- Bug in :func:`date_range` was raising ``AmbiguousTimeError`` for valid input \ 
with ``ambiguous=False`` (:issue:`35297`)
- Bug in :meth:`Timestamp.replace` was losing fold information (:issue:`37610`)

Numeric
- Bug in :func:`to_numeric` where float precision was incorrect (:issue:`31364`)
- Bug in :meth:`DataFrame.any` with ``axis=1`` and ``bool_only=True`` ignoring \ 
the ``bool_only`` keyword (:issue:`32432`)
- Bug in :meth:`Series.equals` where a ``ValueError`` was raised when NumPy \ 
arrays were compared to scalars (:issue:`35267`)
- Bug in :class:`Series` where two Series each have a :class:`.DatetimeIndex` \ 
with different time zones having those indexes incorrectly changed when \ 
performing arithmetic operations (:issue:`33671`)
- Bug in :mod:`pandas.testing` module functions when used with \ 
``check_exact=False`` on complex numeric types (:issue:`28235`)
- Bug in :meth:`DataFrame.__rmatmul__` error handling reporting transposed \ 
shapes (:issue:`21581`)
- Bug in :class:`Series` flex arithmetic methods where the result when operating \ 
with a ``list``, ``tuple`` or ``np.ndarray`` would have an incorrect name \ 
(:issue:`36760`)
- Bug in :class:`.IntegerArray` multiplication with ``timedelta`` and \ 
``np.timedelta64`` objects (:issue:`36870`)
- Bug in :class:`MultiIndex` comparison with tuple incorrectly treating tuple as \ 
array-like (:issue:`21517`)
- Bug in :meth:`DataFrame.diff` with ``datetime64`` dtypes including ``NaT`` \ 
values failing to fill ``NaT`` results correctly (:issue:`32441`)
- Bug in :class:`DataFrame` arithmetic ops incorrectly accepting keyword \ 
arguments (:issue:`36843`)
- Bug in :class:`.IntervalArray` comparisons with :class:`Series` not returning \ 
Series (:issue:`36908`)
- Bug in :class:`DataFrame` allowing arithmetic operations with list of \ 
array-likes with undefined results. Behavior changed to raising ``ValueError`` \ 
(:issue:`36702`)
- Bug in :meth:`DataFrame.std` with ``timedelta64`` dtype and ``skipna=False`` \ 
(:issue:`37392`)
- Bug in :meth:`DataFrame.min` and :meth:`DataFrame.max` with ``datetime64`` \ 
dtype and ``skipna=False`` (:issue:`36907`)
- Bug in :meth:`DataFrame.idxmax` and :meth:`DataFrame.idxmin` with mixed dtypes \ 
incorrectly raising ``TypeError`` (:issue:`38195`)

Conversion
- Bug in :meth:`DataFrame.to_dict` with ``orient='records'`` now returns python \ 
native datetime objects for datetime-like columns (:issue:`21256`)
- Bug in :meth:`Series.astype` conversion from ``string`` to ``float`` raised in \ 
presence of ``pd.NA`` values (:issue:`37626`)

Strings
- Bug in :meth:`Series.to_string`, :meth:`DataFrame.to_string`, and \ 
:meth:`DataFrame.to_latex` adding a leading space when ``index=False`` \ 
(:issue:`24980`)
- Bug in :func:`to_numeric` raising a ``TypeError`` when attempting to convert a \ 
string dtype Series containing only numeric strings and ``NA`` (:issue:`37262`)

Interval
- Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` where \ 
:class:`Interval` dtypes would be converted to object dtypes (:issue:`34871`)
- Bug in :meth:`IntervalIndex.take` with negative indices and \ 
``fill_value=None`` (:issue:`37330`)
- Bug in :meth:`IntervalIndex.putmask` with datetime-like dtype incorrectly \ 
casting to object dtype (:issue:`37968`)
- Bug in :meth:`IntervalArray.astype` incorrectly dropping dtype information \ 
with a :class:`CategoricalDtype` object (:issue:`37984`)

Indexing
- Bug in :meth:`PeriodIndex.get_loc` incorrectly raising ``ValueError`` on \ 
non-datelike strings instead of ``KeyError``, causing similar errors in \ 
:meth:`Series.__getitem__`, :meth:`Series.__contains__`, and \ 
:meth:`Series.loc.__getitem__` (:issue:`34240`)
- Bug in :meth:`Index.sort_values` where, when empty values were passed, the \ 
method would break by trying to compare missing values instead of pushing them \ 
to the end of the sort order (:issue:`35584`)
- Bug in :meth:`Index.get_indexer` and :meth:`Index.get_indexer_non_unique` \ 
where ``int64`` arrays are returned instead of ``intp`` (:issue:`36359`)
- Bug in :meth:`DataFrame.sort_index` where parameter ascending passed as a list \ 
on a single level index gives wrong result (:issue:`32334`)
- Bug in :meth:`DataFrame.reset_index` was incorrectly raising a ``ValueError`` \ 
for input with a :class:`MultiIndex` with missing values in a level with \ 
``Categorical`` dtype (:issue:`24206`)
- Bug in indexing with boolean masks on datetime-like values sometimes returning \ 
a view instead of a copy (:issue:`36210`)
- Bug in :meth:`DataFrame.__getitem__` and :meth:`DataFrame.loc.__getitem__` \ 
with :class:`IntervalIndex` columns and a numeric indexer (:issue:`26490`)
- Bug in :meth:`Series.loc.__getitem__` with a non-unique :class:`MultiIndex` \ 
and an empty-list indexer (:issue:`13691`)
- Bug in indexing on a :class:`Series` or :class:`DataFrame` with a \ 
:class:`MultiIndex` and a level named ``"0"`` (:issue:`37194`)
- Bug in :meth:`Series.__getitem__` when using an unsigned integer array as an \ 
indexer giving incorrect results or segfaulting instead of raising ``KeyError`` \ 
(:issue:`37218`)
- Bug in :meth:`Index.where` incorrectly casting numeric values to strings \ 
(:issue:`37591`)
- Bug in :meth:`DataFrame.loc` returning empty result when indexer is a slice \ 
with negative step size (:issue:`38071`)
- Bug in :meth:`Series.loc` and :meth:`DataFrame.loc` raises when the index was \ 
of ``object`` dtype and the given numeric label was in the index \ 
(:issue:`26491`)
- Bug in :meth:`DataFrame.loc` returned requested key plus missing values when \ 
``loc`` was applied to single level from a :class:`MultiIndex` (:issue:`27104`)
- Bug in indexing on a :class:`Series` or :class:`DataFrame` with a \ 
:class:`CategoricalIndex` using a list-like indexer containing NA values \ 
(:issue:`37722`)
- Bug in :meth:`DataFrame.loc.__setitem__` expanding an empty :class:`DataFrame` \ 
with mixed dtypes (:issue:`37932`)
- Bug in :meth:`DataFrame.xs` ignored ``droplevel=False`` for columns \ 
(:issue:`19056`)
- Bug in :meth:`DataFrame.reindex` raising ``IndexingError`` wrongly for empty \ 
DataFrame with ``tolerance`` not ``None`` or ``method="nearest"`` \ 
(:issue:`27315`)
- Bug in indexing on a :class:`Series` or :class:`DataFrame` with a \ 
:class:`CategoricalIndex` using list-like indexer that contains elements that \ 
are in the index's ``categories`` but not in the index itself failing to raise \ 
``KeyError`` (:issue:`37901`)
- Bug on inserting a boolean label into a :class:`DataFrame` with a numeric \ 
:class:`Index` columns incorrectly casting to integer (:issue:`36319`)
- Bug in :meth:`DataFrame.iloc` and :meth:`Series.iloc` aligning objects in \ 
``__setitem__`` (:issue:`22046`)
- Bug in :meth:`MultiIndex.drop` does not raise if labels are partially found \ 
(:issue:`37820`)
- Bug in :meth:`DataFrame.loc` did not raise ``KeyError`` when missing \ 
combination was given with ``slice(None)`` for remaining levels (:issue:`19556`)
- Bug in :meth:`DataFrame.loc` raising ``TypeError`` when non-integer slice was \ 
given to select values from :class:`MultiIndex` (:issue:`25165`, :issue:`24263`)
- Bug in :meth:`Series.at` returning :class:`Series` with one element instead of \ 
scalar when index is a :class:`MultiIndex` with one level (:issue:`38053`)
- Bug in :meth:`DataFrame.loc` returning and assigning elements in wrong order \ 
when indexer is differently ordered than the :class:`MultiIndex` to filter \ 
(:issue:`31330`, :issue:`34603`)
- Bug in :meth:`DataFrame.loc` and :meth:`DataFrame.__getitem__`  raising \ 
``KeyError`` when columns were :class:`MultiIndex` with only one level \ 
(:issue:`29749`)
- Bug in :meth:`Series.__getitem__` and :meth:`DataFrame.__getitem__` raising \ 
blank ``KeyError`` without missing keys for :class:`IntervalIndex` \ 
(:issue:`27365`)
- Bug in setting a new label on a :class:`DataFrame` or :class:`Series` with a \ 
:class:`CategoricalIndex` incorrectly raising ``TypeError`` when the new label \ 
is not among the index's categories (:issue:`38098`)
- Bug in :meth:`Series.loc` and :meth:`Series.iloc` raising ``ValueError`` when \ 
inserting a list-like ``np.array``, ``list`` or ``tuple`` in an ``object`` \ 
Series of equal length (:issue:`37748`, :issue:`37486`)
- Bug in :meth:`Series.loc` and :meth:`Series.iloc` setting all the values of an \ 
``object`` Series with those of a list-like ``ExtensionArray`` instead of \ 
inserting it (:issue:`38271`)

Missing
- Bug in :meth:`.SeriesGroupBy.transform` now correctly handles missing values \ 
for ``dropna=False`` (:issue:`35014`)
- Bug in :meth:`Series.nunique` with ``dropna=True`` was returning incorrect \ 
results when both ``NA`` and ``None`` missing values were present \ 
(:issue:`37566`)
- Bug in :meth:`Series.interpolate` where kwarg ``limit_area`` and \ 
``limit_direction`` had no effect when using methods ``pad`` and ``backfill`` \ 
(:issue:`31048`)

MultiIndex
- Bug in :meth:`DataFrame.xs` when used with :class:`IndexSlice` raises \ 
``TypeError`` with message ``"Expected label or tuple of labels"`` \ 
(:issue:`35301`)
- Bug in :meth:`DataFrame.reset_index` with ``NaT`` values in index raises \ 
``ValueError`` with message ``"cannot convert float NaN to integer"`` \ 
(:issue:`36541`)
- Bug in :meth:`DataFrame.combine_first` when used with :class:`MultiIndex` \ 
containing string and ``NaN`` values raises ``TypeError`` (:issue:`36562`)
- Bug in :meth:`MultiIndex.drop` dropped ``NaN`` values when non existing key \ 
was given as input (:issue:`18853`)
- Bug in :meth:`MultiIndex.drop` dropping more values than expected when index \ 
has duplicates and is not sorted (:issue:`33494`)

I/O
- :func:`read_sas` no longer leaks resources on failure (:issue:`35566`)
- Bug in :meth:`DataFrame.to_csv` and :meth:`Series.to_csv` caused a \ 
``ValueError`` when it was called with a filename in combination with ``mode`` \ 
containing a ``b`` (:issue:`35058`)
- Bug in :meth:`read_csv` with ``float_precision='round_trip'`` did not handle \ 
``decimal`` and ``thousands`` parameters (:issue:`35365`)
- :meth:`to_pickle` and :meth:`read_pickle` were closing user-provided file \ 
objects (:issue:`35679`)
- :meth:`to_csv` passes compression arguments for ``'gzip'`` always to \ 
``gzip.GzipFile`` (:issue:`28103`)
- :meth:`to_csv` did not support zip compression for binary file object not \ 
having a filename (:issue:`35058`)
- :meth:`to_csv` and :meth:`read_csv` did not honor ``compression`` and \ 
``encoding`` for path-like objects that are internally converted to file-like \ 
objects (:issue:`35677`, :issue:`26124`, :issue:`32392`)
- :meth:`DataFrame.to_pickle`, :meth:`Series.to_pickle`, and :meth:`read_pickle` \ 
did not support compression for file-objects (:issue:`26237`, :issue:`29054`, \ 
:issue:`29570`)
- Bug in :func:`LongTableBuilder.middle_separator` was duplicating LaTeX \ 
longtable entries in the List of Tables of a LaTeX document (:issue:`34360`)
- Bug in :meth:`read_csv` with ``engine='python'`` truncating data if multiple \ 
items present in first row and first element started with BOM (:issue:`36343`)
- Removed ``private_key`` and ``verbose`` from :func:`read_gbq` as they are no \ 
longer supported in ``pandas-gbq`` (:issue:`34654`, :issue:`30200`)
- Bumped minimum pytables version to 3.5.1 to avoid a ``ValueError`` in \ 
:meth:`read_hdf` (:issue:`24839`)
- Bug in :func:`read_table` and :func:`read_csv` when ``delim_whitespace=True`` \ 
and ``sep=default`` (:issue:`36583`)
- Bug in :meth:`DataFrame.to_json` and :meth:`Series.to_json` when used with \ 
``lines=True`` and ``orient='records'`` the last line of the record is not \ 
appended with 'new line character' (:issue:`36888`)
- Bug in :meth:`read_parquet` with fixed offset time zones. String \ 
representation of time zones was not recognized (:issue:`35997`, :issue:`36004`)
- Bug in :meth:`DataFrame.to_html`, :meth:`DataFrame.to_string`, and \ 
:meth:`DataFrame.to_latex` ignoring the ``na_rep`` argument when \ 
``float_format`` was also specified (:issue:`9046`, :issue:`13828`)
- Bug in output rendering of complex numbers showing too many trailing zeros \ 
(:issue:`36799`)
- Bug in :class:`HDFStore` threw a ``TypeError`` when exporting an empty \ 
DataFrame with ``datetime64[ns, tz]`` dtypes with a fixed HDF5 store \ 
(:issue:`20594`)
- Bug in :class:`HDFStore` was dropping time zone information when exporting a \ 
Series with ``datetime64[ns, tz]`` dtypes with a fixed HDF5 store \ 
(:issue:`20594`)
- :func:`read_csv` was closing user-provided binary file handles when \ 
``engine="c"`` and an ``encoding`` was requested (:issue:`36980`)
- Bug in :meth:`DataFrame.to_hdf` was not dropping missing rows with \ 
``dropna=True`` (:issue:`35719`)
- Bug in :func:`read_html` was raising a ``TypeError`` when supplying a \ 
``pathlib.Path`` argument to the ``io`` parameter (:issue:`37705`)
- :meth:`DataFrame.to_excel`, :meth:`Series.to_excel`, \ 
:meth:`DataFrame.to_markdown`, and :meth:`Series.to_markdown` now support \ 
writing to fsspec URLs such as S3 and Google Cloud Storage (:issue:`33987`)
- Bug in :func:`read_fwf` with ``skip_blank_lines=True`` was not skipping blank \ 
lines (:issue:`37758`)
- Parse missing values using :func:`read_json` with ``dtype=False`` to ``NaN`` \ 
instead of ``None`` (:issue:`28501`)
- :meth:`read_fwf` was inferring compression with ``compression=None`` which was \ 
not consistent with the other ``read_*`` functions (:issue:`37909`)
- :meth:`DataFrame.to_html` was ignoring ``formatters`` argument for \ 
``ExtensionDtype`` columns (:issue:`36525`)
- Bumped minimum xarray version to 0.12.3 to avoid reference to the removed \ 
``Panel`` class (:issue:`27101`, :issue:`37983`)
- :meth:`DataFrame.to_csv` was re-opening file-like handles that also implement \ 
``os.PathLike`` (:issue:`38125`)
- Bug in the conversion of a sliced ``pyarrow.Table`` with missing values to a \ 
DataFrame (:issue:`38525`)
- Bug in :func:`read_sql_table` raising a ``sqlalchemy.exc.OperationalError`` \ 
when column names contained a percentage sign (:issue:`37517`)

Period
- Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` where \ 
:class:`Period` dtypes would be converted to object dtypes (:issue:`34871`)

Plotting
- Bug in :meth:`DataFrame.plot` was rotating xticklabels when ``subplots=True``, \ 
even if the x-axis wasn't an irregular time series (:issue:`29460`)
- Bug in :meth:`DataFrame.plot` where a marker letter in the ``style`` keyword \ 
sometimes caused a ``ValueError`` (:issue:`21003`)
- Bug in :meth:`DataFrame.plot.bar` and :meth:`Series.plot.bar` where ticks \ 
positions were assigned by value order instead of using the actual value for \ 
numeric or a smart ordering for string (:issue:`26186`, :issue:`11465`). This \ 
fix has been reverted in pandas 1.2.1, see :doc:`v1.2.1`
- Twinned axes were losing their tick labels which should only happen to all but \ 
the last row or column of 'externally' shared axes (:issue:`33819`)
- Bug in :meth:`Series.plot` and :meth:`DataFrame.plot` was throwing a \ 
:exc:`ValueError` when the Series or DataFrame was
  indexed by a :class:`.TimedeltaIndex` with a fixed frequency and the x-axis \ 
lower limit was greater than the upper limit (:issue:`37454`)
- Bug in :meth:`.DataFrameGroupBy.boxplot` when ``subplots=False`` would raise a \ 
``KeyError`` (:issue:`16748`)
- Bug in :meth:`DataFrame.plot` and :meth:`Series.plot` was overwriting \ 
matplotlib's shared y axes behavior when no ``sharey`` parameter was passed \ 
(:issue:`37942`)
- Bug in :meth:`DataFrame.plot` was raising a ``TypeError`` with \ 
``ExtensionDtype`` columns (:issue:`32073`)

Styler
- Bug in :meth:`Styler.render` HTML was generated incorrectly because of \ 
formatting error in ``rowspan`` attribute, it now matches with w3 syntax \ 
(:issue:`38234`)

Groupby/resample/rolling
- Bug in :meth:`.DataFrameGroupBy.count` and :meth:`SeriesGroupBy.sum` returning \ 
``NaN`` for missing categories when grouped on multiple ``Categoricals``. Now \ 
returning ``0`` (:issue:`35028`)
- Bug in :meth:`.DataFrameGroupBy.apply` that would sometimes throw an erroneous \ 
``ValueError`` if the grouping axis had duplicate entries (:issue:`16646`)
- Bug in :meth:`DataFrame.resample` that would throw a ``ValueError`` when \ 
resampling from ``"D"`` to ``"24H"`` over a transition into \ 
daylight savings time (DST) (:issue:`35219`)
- Bug when combining methods :meth:`DataFrame.groupby` with \ 
:meth:`DataFrame.resample` and :meth:`DataFrame.interpolate` raising a \ 
``TypeError`` (:issue:`35325`)
- Bug in :meth:`.DataFrameGroupBy.apply` where a non-nuisance grouping column \ 
would be dropped from the output columns if another groupby method was called \ 
before ``.apply`` (:issue:`34656`)
- Bug when subsetting columns on a \ 
:class:`~pandas.core.groupby.DataFrameGroupBy` (e.g. \ 
``df.groupby('a')[['b']])``) would reset the attributes ``axis``, ``dropna``, \ 
``group_keys``, ``level``, ``mutated``, ``sort``, and ``squeeze`` to their \ 
default values (:issue:`9959`)
- Bug in :meth:`.DataFrameGroupBy.tshift` failing to raise ``ValueError`` when a \ 
frequency cannot be inferred for the index of a group (:issue:`35937`)
- Bug in :meth:`DataFrame.groupby` does not always maintain column index name \ 
for ``any``, ``all``, ``bfill``, ``ffill``, ``shift`` (:issue:`29764`)
- Bug in :meth:`.DataFrameGroupBy.apply` raising error with ``np.nan`` group(s) \ 
when ``dropna=False`` (:issue:`35889`)
- Bug in :meth:`.Rolling.sum` returned wrong values when dtypes where mixed \ 
between float and integer and ``axis=1`` (:issue:`20649`, :issue:`35596`)
- Bug in :meth:`.Rolling.count` returned ``np.nan`` with \ 
:class:`~pandas.api.indexers.FixedForwardWindowIndexer` as window, \ 
``min_periods=0`` and only missing values in the window (:issue:`35579`)
- Bug where :class:`pandas.core.window.Rolling` produces incorrect window sizes \ 
when using a ``PeriodIndex`` (:issue:`34225`)
- Bug in :meth:`.DataFrameGroupBy.ffill` and :meth:`.DataFrameGroupBy.bfill` \ 
where a ``NaN`` group would return filled values instead of ``NaN`` when \ 
``dropna=True`` (:issue:`34725`)
- Bug in :meth:`.RollingGroupby.count` where a ``ValueError`` was raised when \ 
specifying the ``closed`` parameter (:issue:`35869`)
- Bug in :meth:`.DataFrameGroupBy.rolling` returning wrong values with partial \ 
centered window (:issue:`36040`)
- Bug in :meth:`.DataFrameGroupBy.rolling` returned wrong values with time aware \ 
window containing ``NaN``. Raises ``ValueError`` because windows are not \ 
monotonic now (:issue:`34617`)
- Bug in :meth:`.Rolling.__iter__` where a ``ValueError`` was not raised when \ 
``min_periods`` was larger than ``window`` (:issue:`37156`)
- Using :meth:`.Rolling.var` instead of :meth:`.Rolling.std` avoids numerical \ 
issues for :meth:`.Rolling.corr` when :meth:`.Rolling.var` is still within \ 
floating point precision while :meth:`.Rolling.std` is not (:issue:`31286`)
- Bug in :meth:`.DataFrameGroupBy.quantile` and :meth:`.Resampler.quantile` \ 
raised ``TypeError`` when values were of type ``Timedelta`` (:issue:`29485`)
- Bug in :meth:`.Rolling.median` and :meth:`.Rolling.quantile` returned wrong \ 
values for :class:`.BaseIndexer` subclasses with non-monotonic starting or \ 
ending points for windows (:issue:`37153`)
- Bug in :meth:`DataFrame.groupby` dropped ``nan`` groups from result with \ 
``dropna=False`` when grouping over a single column (:issue:`35646`, \ 
:issue:`35542`)
- Bug in :meth:`.DataFrameGroupBy.head`, :meth:`DataFrameGroupBy.tail`, \ 
:meth:`SeriesGroupBy.head`, and :meth:`SeriesGroupBy.tail` would raise when used \ 
with ``axis=1`` (:issue:`9772`)
- Bug in :meth:`.DataFrameGroupBy.transform` would raise when used with \ 
``axis=1`` and a transformation kernel (e.g. "shift") (:issue:`36308`)
- Bug in :meth:`.DataFrameGroupBy.resample` using ``.agg`` with sum produced \ 
different result than just calling ``.sum`` (:issue:`33548`)
- Bug in :meth:`.DataFrameGroupBy.apply` dropped values on ``nan`` group when \ 
returning the same axes with the original frame (:issue:`38227`)
- Bug in :meth:`.DataFrameGroupBy.quantile` couldn't handle with arraylike ``q`` \ 
when grouping by columns (:issue:`33795`)
- Bug in :meth:`DataFrameGroupBy.rank` with ``datetime64tz`` or period dtype \ 
incorrectly casting results to those dtypes instead of returning ``float64`` \ 
dtype (:issue:`38187`)

Reshaping
- Bug in :meth:`DataFrame.crosstab` was returning incorrect results on inputs \ 
with duplicate row names, duplicate column names or duplicate names between row \ 
and column labels (:issue:`22529`)
- Bug in :meth:`DataFrame.pivot_table` with ``aggfunc='count'`` or \ 
``aggfunc='sum'`` returning ``NaN`` for missing categories when pivoted on a \ 
``Categorical``. Now returning ``0`` (:issue:`31422`)
- Bug in :func:`concat` and :class:`DataFrame` constructor where input index \ 
names are not preserved in some cases (:issue:`13475`)
- Bug in func :meth:`crosstab` when using multiple columns with ``margins=True`` \ 
and ``normalize=True`` (:issue:`35144`)
- Bug in :meth:`DataFrame.stack` where an empty DataFrame.stack would raise an \ 
error (:issue:`36113`). Now returning an empty Series with empty MultiIndex.
- Bug in :meth:`Series.unstack`. Now a Series with single level of Index trying \ 
to unstack would raise a ``ValueError`` (:issue:`36113`)
- Bug in :meth:`DataFrame.agg` with ``func={'name':<FUNC>}`` incorrectly \ 
raising ``TypeError`` when ``DataFrame.columns==['Name']`` (:issue:`36212`)
- Bug in :meth:`Series.transform` would give incorrect results or raise when the \ 
argument ``func`` was a dictionary (:issue:`35811`)
- Bug in :meth:`DataFrame.pivot` did not preserve :class:`MultiIndex` level \ 
names for columns when rows and columns are both multiindexed (:issue:`36360`)
- Bug in :meth:`DataFrame.pivot` modified ``index`` argument when ``columns`` \ 
was passed but ``values`` was not (:issue:`37635`)
- Bug in :meth:`DataFrame.join` returned a non deterministic level-order for the \ 
resulting :class:`MultiIndex` (:issue:`36910`)
- Bug in :meth:`DataFrame.combine_first` caused wrong alignment with dtype \ 
``string`` and one level of ``MultiIndex`` containing only ``NA`` \ 
(:issue:`37591`)
- Fixed regression in :func:`merge` on merging :class:`.DatetimeIndex` with \ 
empty DataFrame (:issue:`36895`)
- Bug in :meth:`DataFrame.apply` not setting index of return value when ``func`` \ 
return type is ``dict`` (:issue:`37544`)
- Bug in :meth:`DataFrame.merge` and :meth:`pandas.merge` returning inconsistent \ 
ordering in result for ``how=right`` and ``how=left`` (:issue:`35382`)
- Bug in :func:`merge_ordered` couldn't handle list-like ``left_by`` or \ 
``right_by`` (:issue:`35269`)
- Bug in :func:`merge_ordered` returned wrong join result when length of \ 
``left_by`` or ``right_by`` equals to the rows of ``left`` or ``right`` \ 
(:issue:`38166`)
- Bug in :func:`merge_ordered` didn't raise when elements in ``left_by`` or \ 
``right_by`` not exist in ``left`` columns or ``right`` columns (:issue:`38167`)
- Bug in :func:`DataFrame.drop_duplicates` not validating bool dtype for \ 
``ignore_index`` keyword (:issue:`38274`)

ExtensionArray
- Fixed bug where :class:`DataFrame` column set to scalar extension type via a \ 
dict instantiation was considered an object type rather than the extension type \ 
(:issue:`35965`)
- Fixed bug where ``astype()`` with equal dtype and ``copy=False`` would return \ 
a new object (:issue:`28488`)
- Fixed bug when applying a NumPy ufunc with multiple outputs to an \ 
:class:`.IntegerArray` returning ``None`` (:issue:`36913`)
- Fixed an inconsistency in :class:`.PeriodArray`'s ``__init__`` signature to \ 
those of :class:`.DatetimeArray` and :class:`.TimedeltaArray` (:issue:`37289`)
- Reductions for :class:`.BooleanArray`, :class:`.Categorical`, \ 
:class:`.DatetimeArray`, :class:`.FloatingArray`, :class:`.IntegerArray`, \ 
:class:`.PeriodArray`, :class:`.TimedeltaArray`, and :class:`.PandasArray` are \ 
now keyword-only methods (:issue:`37541`)
- Fixed a bug where a  ``TypeError`` was wrongly raised if a membership check \ 
was made on an ``ExtensionArray`` containing nan-like values (:issue:`37867`)

Other
- Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` incorrectly \ 
raising an ``AssertionError`` instead of a ``ValueError`` when invalid parameter \ 
combinations are passed (:issue:`36045`)
- Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` with numeric \ 
values and string ``to_replace`` (:issue:`34789`)
- Fixed metadata propagation in :meth:`Series.abs` and ufuncs called on Series \ 
and DataFrames (:issue:`28283`)
- Bug in :meth:`DataFrame.replace` and :meth:`Series.replace` incorrectly \ 
casting from ``PeriodDtype`` to object dtype (:issue:`34871`)
- Fixed bug in metadata propagation incorrectly copying DataFrame columns as \ 
metadata when the column name overlaps with the metadata name (:issue:`37037`)
- Fixed metadata propagation in the :class:`Series.dt`, :class:`Series.str` \ 
accessors, :class:`DataFrame.duplicated`, :class:`DataFrame.stack`, \ 
:class:`DataFrame.unstack`, :class:`DataFrame.pivot`, :class:`DataFrame.append`, \ 
:class:`DataFrame.diff`, :class:`DataFrame.applymap` and \ 
:class:`DataFrame.update` methods (:issue:`28283`, :issue:`37381`)
- Fixed metadata propagation when selecting columns with \ 
``DataFrame.__getitem__`` (:issue:`28283`)
- Bug in :meth:`Index.intersection` with non-:class:`Index` failing to set the \ 
correct name on the returned :class:`Index` (:issue:`38111`)
- Bug in :meth:`RangeIndex.intersection` failing to set the correct name on the \ 
returned :class:`Index` in some corner cases (:issue:`38197`)
- Bug in :meth:`Index.difference` failing to set the correct name on the \ 
returned :class:`Index` in some corner cases (:issue:`38268`)
- Bug in :meth:`Index.union` behaving differently depending on whether operand \ 
is an :class:`Index` or other list-like (:issue:`36384`)
- Bug in :meth:`Index.intersection` with non-matching numeric dtypes casting to \ 
``object`` dtype instead of minimal common dtype (:issue:`38122`)
- Bug in :meth:`IntervalIndex.union` returning an incorrectly-typed \ 
:class:`Index` when empty (:issue:`38282`)
- Passing an array with 2 or more dimensions to the :class:`Series` constructor \ 
now raises the more specific ``ValueError`` rather than a bare ``Exception`` \ 
(:issue:`35744`)
- Bug in ``dir`` where ``dir(obj)`` wouldn't show attributes defined on the \ 
instance for pandas objects (:issue:`37173`)
- Bug in :meth:`Index.drop` raising ``InvalidIndexError`` when index has \ 
duplicates (:issue:`38051`)
- Bug in :meth:`RangeIndex.difference` returning :class:`Int64Index` in some \ 
cases where it should return :class:`RangeIndex` (:issue:`38028`)
- Fixed bug in :func:`assert_series_equal` when comparing a datetime-like array \ 
with an equivalent non extension dtype array (:issue:`37609`)
- Bug in :func:`.is_bool_dtype` would raise when passed a valid string such as \ 
``"boolean"`` (:issue:`38386`)
- Fixed regression in logical operators raising ``ValueError`` when columns of \ 
:class:`DataFrame` are a :class:`CategoricalIndex` with unused categories \ 
(:issue:`38367`)