Auto backport of pr 27580 on 0.25.x

Makefile

@@ -15,7 +15,7 @@ lint-diff:
 	git diff upstream/master --name-only -- "*.py" | xargs flake8
 
 black:
-	black . --exclude '(asv_bench/env|\.egg|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)'
+	black . --exclude '(asv_bench/env|\.egg|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist|setup.py)'
 
 develop: build
 	python setup.py develop

ci/code_checks.sh

@@ -56,7 +56,7 @@ if [[ -z "$CHECK" || "$CHECK" == "lint" ]]; then
     black --version
 
     MSG='Checking black formatting' ; echo $MSG
-	black . --check --exclude '(asv_bench/env|\.egg|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist)'
+	black . --check --exclude '(asv_bench/env|\.egg|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist|setup.py)'
     RET=$(($RET + $?)) ; echo $MSG "DONE"
 
     # `setup.cfg` contains the list of error codes that are being ignored in flake8

doc/source/development/extending.rst

@@ -441,5 +441,22 @@ This would be more or less equivalent to:
 The backend module can then use other visualization tools (Bokeh, Altair,...)
 to generate the plots.
 
+Libraries implementing the plotting backend should use `entry points <https://setuptools.readthedocs.io/en/latest/setuptools.html#dynamic-discovery-of-services-and-plugins>`__
+to make their backend discoverable to pandas. The key is ``"pandas_plotting_backends"``. For example, pandas
+registers the default "matplotlib" backend as follows.
+
+.. code-block:: python
+
+   # in setup.py
+   setup(  # noqa: F821
+       ...,
+       entry_points={
+           "pandas_plotting_backends": [
+               "matplotlib = pandas:plotting._matplotlib",
+           ],
+       },
+   )
+
+
 More information on how to implement a third-party plotting backend can be found at
 https://github.com/pandas-dev/pandas/blob/master/pandas/plotting/__init__.py#L1.

doc/source/install.rst

@@ -15,35 +15,10 @@ Instructions for installing from source,
 `PyPI <https://pypi.org/project/pandas>`__, `ActivePython <https://www.activestate.com/activepython/downloads>`__, various Linux distributions, or a
 `development version <http://github.com/pandas-dev/pandas>`__ are also provided.
 
-.. _install.dropping-27:
-
-Plan for dropping Python 2.7
-----------------------------
-
-The Python core team plans to stop supporting Python 2.7 on January 1st, 2020.
-In line with `NumPy's plans`_, all pandas releases through December 31, 2018
-will support Python 2.
-
-The 0.24.x feature release will be the last release to
-support Python 2. The released package will continue to be available on
-PyPI and through conda.
-
- Starting **January 1, 2019**, all new feature releases (> 0.24) will be Python 3 only.
-
-If there are people interested in continued support for Python 2.7 past December
-31, 2018 (either backporting bug fixes or funding) please reach out to the
-maintainers on the issue tracker.
-
-For more information, see the `Python 3 statement`_ and the `Porting to Python 3 guide`_.
-
-.. _NumPy's plans: https://github.com/numpy/numpy/blob/master/doc/neps/nep-0014-dropping-python2.7-proposal.rst#plan-for-dropping-python-27-support
-.. _Python 3 statement: http://python3statement.org/
-.. _Porting to Python 3 guide: https://docs.python.org/3/howto/pyporting.html
-
 Python version support
 ----------------------
 
-Officially Python 2.7, 3.5, 3.6, and 3.7.
+Officially Python 3.5.3 and above, 3.6, and 3.7.
 
 Installing pandas
 -----------------

doc/source/whatsnew/v0.23.0.rst

@@ -31,7 +31,7 @@ Check the :ref:`API Changes <whatsnew_0230.api_breaking>` and :ref:`deprecations
 .. warning::
 
    Starting January 1, 2019, pandas feature releases will support Python 3 only.
-   See :ref:`install.dropping-27` for more.
+   See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 .. contents:: What's new in v0.23.0
     :local:

doc/source/whatsnew/v0.23.1.rst

@@ -12,7 +12,7 @@ and bug fixes. We recommend that all users upgrade to this version.
 .. warning::
 
    Starting January 1, 2019, pandas feature releases will support Python 3 only.
-   See :ref:`install.dropping-27` for more.
+   See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 .. contents:: What's new in v0.23.1
     :local:

doc/source/whatsnew/v0.23.2.rst

@@ -17,7 +17,7 @@ and bug fixes. We recommend that all users upgrade to this version.
 .. warning::
 
    Starting January 1, 2019, pandas feature releases will support Python 3 only.
-   See :ref:`install.dropping-27` for more.
+   See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 .. contents:: What's new in v0.23.2
     :local:

doc/source/whatsnew/v0.23.4.rst

@@ -12,7 +12,7 @@ and bug fixes. We recommend that all users upgrade to this version.
 .. warning::
 
    Starting January 1, 2019, pandas feature releases will support Python 3 only.
-   See :ref:`install.dropping-27` for more.
+   See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 .. contents:: What's new in v0.23.4
     :local:

doc/source/whatsnew/v0.24.0.rst

@@ -6,7 +6,7 @@ What's new in 0.24.0 (January 25, 2019)
 .. warning::
 
    The 0.24.x series of releases will be the last to support Python 2. Future feature
-   releases will support Python 3 only. See :ref:`install.dropping-27` for more
+   releases will support Python 3 only. See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more
    details.
 
 {{ header }}

doc/source/whatsnew/v0.24.1.rst

@@ -6,7 +6,7 @@ Whats new in 0.24.1 (February 3, 2019)
 .. warning::
 
    The 0.24.x series of releases will be the last to support Python 2. Future feature
-   releases will support Python 3 only. See :ref:`install.dropping-27` for more.
+   releases will support Python 3 only. See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 {{ header }}
 

doc/source/whatsnew/v0.24.2.rst

@@ -6,7 +6,7 @@ Whats new in 0.24.2 (March 12, 2019)
 .. warning::
 
    The 0.24.x series of releases will be the last to support Python 2. Future feature
-   releases will support Python 3 only. See :ref:`install.dropping-27` for more.
+   releases will support Python 3 only. See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more.
 
 {{ header }}
 

doc/source/whatsnew/v0.25.0.rst

@@ -6,7 +6,7 @@ What's new in 0.25.0 (July 18, 2019)
 .. warning::
 
    Starting with the 0.25.x series of releases, pandas only supports Python 3.5.3 and higher.
-   See :ref:`install.dropping-27` for more details.
+   See `Dropping Python 2.7 <https://pandas.pydata.org/pandas-docs/version/0.24/install.html#install-dropping-27>`_ for more details.
 
 .. warning::
 

doc/source/whatsnew/v0.25.1.rst

@@ -50,20 +50,21 @@ Timedelta
 Timezones
 ^^^^^^^^^
 
--
+- Bug in :class:`Index` where a numpy object array with a timezone aware :class:`Timestamp` and ``np.nan`` would not return a :class:`DatetimeIndex` (:issue:`27011`)
 -
 -
 
 Numeric
 ^^^^^^^
--
+- Bug in :meth:`Series.interpolate` when using a timezone aware :class:`DatetimeIndex` (:issue:`27548`)
+- Bug when printing negative floating point complex numbers would raise an ``IndexError`` (:issue:`27484`)
 -
 -
 
 Conversion
 ^^^^^^^^^^
 
--
+- Improved the warnings for the deprecated methods :meth:`Series.real` and :meth:`Series.imag` (:issue:`27610`)
 -
 -
 
@@ -113,21 +114,21 @@ I/O
 Plotting
 ^^^^^^^^
 
--
+- Added a pandas_plotting_backends entrypoint group for registering plot backends. See :ref:`extending.plotting-backends` for more (:issue:`26747`).
 -
 -
 
 Groupby/resample/rolling
 ^^^^^^^^^^^^^^^^^^^^^^^^
 
--
+- Bug in :meth:`pandas.core.groupby.DataFrameGroupBy.transform` where applying a timezone conversion lambda function would drop timezone information (:issue:`27496`)
 -
 -
 
 Reshaping
 ^^^^^^^^^
 
--
+- A ``KeyError`` is now raised if ``.unstack()`` is called on a :class:`Series` or :class:`DataFrame` with a flat :class:`Index` passing a name which is not the correct one (:issue:`18303`)
 -
 -
 

pandas/core/frame.py

@@ -2601,12 +2601,12 @@ def memory_usage(self, index=True, deep=False):
         ...              for t in dtypes])
         >>> df = pd.DataFrame(data)
         >>> df.head()
-           int64  float64  complex128  object  bool
-        0      1      1.0    1.0+0.0j       1  True
-        1      1      1.0    1.0+0.0j       1  True
-        2      1      1.0    1.0+0.0j       1  True
-        3      1      1.0    1.0+0.0j       1  True
-        4      1      1.0    1.0+0.0j       1  True
+           int64  float64            complex128  object  bool
+        0      1      1.0    1.000000+0.000000j       1  True
+        1      1      1.0    1.000000+0.000000j       1  True
+        2      1      1.0    1.000000+0.000000j       1  True
+        3      1      1.0    1.000000+0.000000j       1  True
+        4      1      1.0    1.000000+0.000000j       1  True
 
         >>> df.memory_usage()
         Index           128

pandas/core/generic.py

@@ -30,7 +30,6 @@
     is_bool,
     is_bool_dtype,
     is_datetime64_any_dtype,
-    is_datetime64_dtype,
     is_datetime64tz_dtype,
     is_dict_like,
     is_extension_array_dtype,
@@ -7035,7 +7034,7 @@ def interpolate(
             methods = {"index", "values", "nearest", "time"}
             is_numeric_or_datetime = (
                 is_numeric_dtype(index)
-                or is_datetime64_dtype(index)
+                or is_datetime64_any_dtype(index)
                 or is_timedelta64_dtype(index)
             )
             if method not in methods and not is_numeric_or_datetime:

pandas/core/groupby/generic.py

@@ -42,7 +42,7 @@
 from pandas.core.base import DataError, SpecificationError
 import pandas.core.common as com
 from pandas.core.frame import DataFrame
-from pandas.core.generic import NDFrame, _shared_docs
+from pandas.core.generic import ABCDataFrame, ABCSeries, NDFrame, _shared_docs
 from pandas.core.groupby import base
 from pandas.core.groupby.groupby import GroupBy, _apply_docs, _transform_template
 from pandas.core.index import Index, MultiIndex
@@ -1025,8 +1025,8 @@ def transform(self, func, *args, **kwargs):
             object.__setattr__(group, "name", name)
             res = wrapper(group)
 
-            if hasattr(res, "values"):
-                res = res.values
+            if isinstance(res, (ABCDataFrame, ABCSeries)):
+                res = res._values
 
             indexer = self._get_index(name)
             s = klass(res, indexer)

pandas/core/indexes/base.py

@@ -489,19 +489,15 @@ def __new__(
                     pass
                 elif inferred != "string":
                     if inferred.startswith("datetime"):
-                        if (
-                            lib.is_datetime_with_singletz_array(subarr)
-                            or "tz" in kwargs
-                        ):
-                            # only when subarr has the same tz
-                            from pandas import DatetimeIndex
+                        from pandas import DatetimeIndex
 
-                            try:
-                                return DatetimeIndex(
-                                    subarr, copy=copy, name=name, **kwargs
-                                )
-                            except OutOfBoundsDatetime:
-                                pass
+                        try:
+                            return DatetimeIndex(subarr, copy=copy, name=name, **kwargs)
+                        except (ValueError, OutOfBoundsDatetime):
+                            # GH 27011
+                            # If we have mixed timezones, just send it
+                            # down the base constructor
+                            pass
 
                     elif inferred.startswith("timedelta"):
                         from pandas import TimedeltaIndex
@@ -1550,7 +1546,11 @@ def _validate_index_level(self, level):
                     "Too many levels:" " Index has only 1 level, not %d" % (level + 1)
                 )
         elif level != self.name:
-            raise KeyError("Level %s must be same as name (%s)" % (level, self.name))
+            raise KeyError(
+                "Requested level ({}) does not match index name ({})".format(
+                    level, self.name
+                )
+            )
 
     def _get_level_number(self, level):
         self._validate_index_level(level)

pandas/core/reshape/reshape.py

@@ -12,6 +12,7 @@
     ensure_platform_int,
     is_bool_dtype,
     is_extension_array_dtype,
+    is_integer,
     is_integer_dtype,
     is_list_like,
     is_object_dtype,
@@ -402,6 +403,10 @@ def unstack(obj, level, fill_value=None):
         else:
             level = level[0]
 
+    # Prioritize integer interpretation (GH #21677):
+    if not is_integer(level) and not level == "__placeholder__":
+        level = obj.index._get_level_number(level)
+
     if isinstance(obj, DataFrame):
         if isinstance(obj.index, MultiIndex):
             return _unstack_frame(obj, level, fill_value=fill_value)

pandas/core/series.py

@@ -958,7 +958,9 @@ def real(self):
         .. deprecated 0.25.0
         """
         warnings.warn(
-            "`real` has be deprecated and will be removed in a " "future verison",
+            "`real` is deprecated and will be removed in a future version. "
+            "To eliminate this warning for a Series `ser`, use "
+            "`np.real(ser.to_numpy())` or `ser.to_numpy().real`.",
             FutureWarning,
             stacklevel=2,
         )
@@ -976,7 +978,9 @@ def imag(self):
         .. deprecated 0.25.0
         """
         warnings.warn(
-            "`imag` has be deprecated and will be removed in a " "future verison",
+            "`imag` is deprecated and will be removed in a future version. "
+            "To eliminate this warning for a Series `ser`, use "
+            "`np.imag(ser.to_numpy())` or `ser.to_numpy().imag`.",
             FutureWarning,
             stacklevel=2,
         )

pandas/io/formats/format.py

@@ -5,6 +5,7 @@
 
 from functools import partial
 from io import StringIO
+import re
 from shutil import get_terminal_size
 from unicodedata import east_asian_width
 
@@ -1584,17 +1585,10 @@ def _trim_zeros_complex(str_complexes, na_rep="NaN"):
     Separates the real and imaginary parts from the complex number, and
     executes the _trim_zeros_float method on each of those.
     """
-
-    def separate_and_trim(str_complex, na_rep):
-        num_arr = str_complex.split("+")
-        return (
-            _trim_zeros_float([num_arr[0]], na_rep)
-            + ["+"]
-            + _trim_zeros_float([num_arr[1][:-1]], na_rep)
-            + ["j"]
-        )
-
-    return ["".join(separate_and_trim(x, na_rep)) for x in str_complexes]
+    return [
+        "".join(_trim_zeros_float(re.split(r"([j+-])", x), na_rep))
+        for x in str_complexes
+    ]
 
 
 def _trim_zeros_float(str_floats, na_rep="NaN"):