These are the changes in pandas 2.2.0. See :ref:`release` for a full changelog including other versions of pandas.
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These are bug fixes that might have notable behavior changes.
:func:`merge` and :meth:`DataFrame.join` now consistently follow documented sort behavior
In previous versions of pandas, :func:`merge` and :meth:`DataFrame.join` did not always return a result that followed the documented sort behavior. pandas now follows the documented sort behavior in merge and join operations (:issue:`54611`).
As documented, sort=True sorts the join keys lexicographically in the resulting
:class:`DataFrame`. With sort=False, the order of the join keys depends on the
join type (how keyword):
how="left": preserve the order of the left keyshow="right": preserve the order of the right keyshow="inner": preserve the order of the left keyshow="outer": sort keys lexicographically
One example with changing behavior is inner joins with non-unique left join keys
and sort=False:
.. ipython:: python
left = pd.DataFrame({"a": [1, 2, 1]})
right = pd.DataFrame({"a": [1, 2]})
result = pd.merge(left, right, how="inner", on="a", sort=False)
Old Behavior
In [5]: result
Out[5]:
a
0 1
1 1
2 2
New Behavior
.. ipython:: python
result
Some minimum supported versions of dependencies were updated. If installed, we now require:
| Package | Minimum Version | Required | Changed |
|---|---|---|---|
| X | X |
For optional libraries the general recommendation is to use the latest version. The following table lists the lowest version per library that is currently being tested throughout the development of pandas. Optional libraries below the lowest tested version may still work, but are not considered supported.
| Package | Minimum Version | Changed |
|---|---|---|
| X |
See :ref:`install.dependencies` and :ref:`install.optional_dependencies` for more.
- Changed :meth:`Timedelta.resolution_string` to return
min,s,ms,us, andnsinstead ofT,S,L,U, andN, for compatibility with respective deprecations in frequency aliases (:issue:`52536`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_clipboard`. (:issue:`54229`)
- Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_csv` except
path_or_buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_dict`. (:issue:`54229`)
- Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_excel` except
excel_writer. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_gbq` except
destination_table. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_hdf` except
path_or_buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_html` except
buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_json` except
path_or_buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_latex` except
buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_markdown` except
buf. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_parquet` except
path. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_pickle` except
path. (:issue:`54229`) - Deprecated allowing non-keyword arguments in :meth:`DataFrame.to_string` except
buf. (:issue:`54229`) - Deprecated downcasting behavior in :meth:`Series.where`, :meth:`DataFrame.where`, :meth:`Series.mask`, :meth:`DataFrame.mask`, :meth:`Series.clip`, :meth:`DataFrame.clip`; in a future version these will not infer object-dtype columns to non-object dtype, or all-round floats to integer dtype. Call
result.infer_objects(copy=False)on the result for object inference, or explicitly cast floats to ints. To opt in to the future version, usepd.set_option("future.downcasting", True)(:issue:`53656`) - Deprecated including the groups in computations when using :meth:`DataFrameGroupBy.apply` and :meth:`DataFrameGroupBy.resample`; pass
include_groups=Falseto exclude the groups (:issue:`7155`) - Deprecated not passing a tuple to :class:`DataFrameGroupBy.get_group` or :class:`SeriesGroupBy.get_group` when grouping by a length-1 list-like (:issue:`25971`)
- Deprecated strings
S,U, andNdenoting units in :func:`to_timedelta` (:issue:`52536`) - Deprecated strings
T,S,L,U, andNdenoting frequencies in :class:`Minute`, :class:`Second`, :class:`Milli`, :class:`Micro`, :class:`Nano` (:issue:`52536`) - Deprecated strings
T,S,L,U, andNdenoting units in :class:`Timedelta` (:issue:`52536`) - Deprecated the extension test classes
BaseNoReduceTests,BaseBooleanReduceTests, andBaseNumericReduceTests, useBaseReduceTestsinstead (:issue:`54663`)
- Performance improvement in :func:`to_dict` on converting DataFrame to dictionary (:issue:`50990`)
- Performance improvement in :meth:`DataFrame.sort_index` and :meth:`Series.sort_index` when indexed by a :class:`MultiIndex` (:issue:`54835`)
- Performance improvement when indexing with more than 4 keys (:issue:`54550`)
- Bug in :class:`AbstractHolidayCalendar` where timezone data was not propagated when computing holiday observances (:issue:`54580`)
- Bug in :func:`read_csv` with
engine="pyarrow"causing rounding errors for large integers (:issue:`52505`)
- Bug in :func:`read_excel`, with
engine="xlrd"(xlsfiles) erroring when file contains NaNs/Infs (:issue:`54564`)