REF: Prefer testing and documenting zoneinfo instead of pytz (#59016)

* REF: Prefer testing and documenting zoneinfo instead of pytz

* Fix tests

* Remove bad test case, fix bad attribute

asv_bench/benchmarks/tslibs/timestamp.py

@@ -1,7 +1,10 @@
-from datetime import datetime
+from datetime import (
+    datetime,
+    timezone,
+)
+import zoneinfo
 
 import numpy as np
-import pytz
 
 from pandas import Timestamp
 
@@ -12,7 +15,7 @@ class TimestampConstruction:
     def setup(self):
         self.npdatetime64 = np.datetime64("2020-01-01 00:00:00")
         self.dttime_unaware = datetime(2020, 1, 1, 0, 0, 0)
-        self.dttime_aware = datetime(2020, 1, 1, 0, 0, 0, 0, pytz.UTC)
+        self.dttime_aware = datetime(2020, 1, 1, 0, 0, 0, 0, timezone.utc)
         self.ts = Timestamp("2020-01-01 00:00:00")
 
     def time_parse_iso8601_no_tz(self):
@@ -113,7 +116,7 @@ def setup(self, tz):
         self.ts = Timestamp("2017-08-25 08:16:14", tz=tz)
 
     def time_replace_tz(self, tz):
-        self.ts.replace(tzinfo=pytz.timezone("US/Eastern"))
+        self.ts.replace(tzinfo=zoneinfo.ZoneInfo("US/Eastern"))
 
     def time_replace_None(self, tz):
         self.ts.replace(tzinfo=None)
@@ -144,8 +147,8 @@ def time_ceil(self, tz):
 
 class TimestampAcrossDst:
     def setup(self):
-        dt = datetime(2016, 3, 27, 1)
-        self.tzinfo = pytz.timezone("CET").localize(dt, is_dst=False).tzinfo
+        dt = datetime(2016, 3, 27, 1, fold=0)
+        self.tzinfo = dt.astimezone(zoneinfo.ZoneInfo("Europe/Berlin")).tzinfo
         self.ts2 = Timestamp(dt)
 
     def time_replace_across_dst(self):

asv_bench/benchmarks/tslibs/tslib.py

@@ -20,13 +20,13 @@
     timedelta,
     timezone,
 )
+import zoneinfo
 
 from dateutil.tz import (
     gettz,
     tzlocal,
 )
 import numpy as np
-import pytz
 
 try:
     from pandas._libs.tslibs import ints_to_pydatetime
@@ -38,7 +38,7 @@
     None,
     timezone.utc,
     timezone(timedelta(minutes=60)),
-    pytz.timezone("US/Pacific"),
+    zoneinfo.ZoneInfo("US/Pacific"),
     gettz("Asia/Tokyo"),
     tzlocal_obj,
 ]

asv_bench/benchmarks/tslibs/tz_convert.py

@@ -1,5 +1,6 @@
+from datetime import timezone
+
 import numpy as np
-from pytz import UTC
 
 from pandas._libs.tslibs.tzconversion import tz_localize_to_utc
 
@@ -41,7 +42,7 @@ def time_tz_convert_from_utc(self, size, tz):
         #  dti = DatetimeIndex(self.i8data, tz=tz)
         #  dti.tz_localize(None)
         if old_sig:
-            tz_convert_from_utc(self.i8data, UTC, tz)
+            tz_convert_from_utc(self.i8data, timezone.utc, tz)
         else:
             tz_convert_from_utc(self.i8data, tz)
 

doc/source/user_guide/io.rst

@@ -4990,7 +4990,7 @@ Caveats
   convenience you can use ``store.flush(fsync=True)`` to do this for you.
 * Once a ``table`` is created columns (DataFrame)
   are fixed; only exactly the same columns can be appended
-* Be aware that timezones (e.g., ``pytz.timezone('US/Eastern')``)
+* Be aware that timezones (e.g., ``zoneinfo.ZoneInfo('US/Eastern')``)
   are not necessarily equal across timezone versions.  So if data is
   localized to a specific timezone in the HDFStore using one version
   of a timezone library and that data is updated with another version, the data
@@ -5169,6 +5169,8 @@ See the `Full Documentation <https://github.com/wesm/feather>`__.
 
 .. ipython:: python
 
+   import pytz
+
    df = pd.DataFrame(
        {
            "a": list("abc"),
@@ -5178,7 +5180,7 @@ See the `Full Documentation <https://github.com/wesm/feather>`__.
            "e": [True, False, True],
            "f": pd.Categorical(list("abc")),
            "g": pd.date_range("20130101", periods=3),
-           "h": pd.date_range("20130101", periods=3, tz="US/Eastern"),
+           "h": pd.date_range("20130101", periods=3, tz=pytz.timezone("US/Eastern")),
            "i": pd.date_range("20130101", periods=3, freq="ns"),
        }
    )

doc/source/user_guide/timeseries.rst

@@ -2337,7 +2337,7 @@ Time zone handling
 ------------------
 
 pandas provides rich support for working with timestamps in different time
-zones using the ``pytz`` and ``dateutil`` libraries or :class:`datetime.timezone`
+zones using the ``zoneinfo``, ``pytz`` and ``dateutil`` libraries or :class:`datetime.timezone`
 objects from the standard library.
 
 
@@ -2354,14 +2354,14 @@ By default, pandas objects are time zone unaware:
 To localize these dates to a time zone (assign a particular time zone to a naive date),
 you can use the ``tz_localize`` method or the ``tz`` keyword argument in
 :func:`date_range`, :class:`Timestamp`, or :class:`DatetimeIndex`.
-You can either pass ``pytz`` or ``dateutil`` time zone objects or Olson time zone database strings.
+You can either pass ``zoneinfo``, ``pytz`` or ``dateutil`` time zone objects or Olson time zone database strings.
 Olson time zone strings will return ``pytz`` time zone objects by default.
 To return ``dateutil`` time zone objects, append ``dateutil/`` before the string.
 
-* In ``pytz`` you can find a list of common (and less common) time zones using
-  ``from pytz import common_timezones, all_timezones``.
+* For ``zoneinfo``, a list of available timezones are available from :py:func:`zoneinfo.available_timezones`.
+* In ``pytz`` you can find a list of common (and less common) time zones using ``pytz.all_timezones``.
 * ``dateutil`` uses the OS time zones so there isn't a fixed list available. For
-  common zones, the names are the same as ``pytz``.
+  common zones, the names are the same as ``pytz`` and ``zoneinfo``.
 
 .. ipython:: python
 
@@ -2466,7 +2466,7 @@ you can use the ``tz_convert`` method.
 
 .. warning::
 
-    If you are using dates beyond 2038-01-18, due to current deficiencies
+    If you are using dates beyond 2038-01-18 with ``pytz``, due to current deficiencies
     in the underlying libraries caused by the year 2038 problem, daylight saving time (DST) adjustments
     to timezone aware dates will not be applied. If and when the underlying libraries are fixed,
     the DST transitions will be applied.
@@ -2475,9 +2475,11 @@ you can use the ``tz_convert`` method.
 
     .. ipython:: python
 
+      import pytz
+
        d_2037 = "2037-03-31T010101"
        d_2038 = "2038-03-31T010101"
-       DST = "Europe/London"
+       DST = pytz.timezone("Europe/London")
        assert pd.Timestamp(d_2037, tz=DST) != pd.Timestamp(d_2037, tz="GMT")
        assert pd.Timestamp(d_2038, tz=DST) == pd.Timestamp(d_2038, tz="GMT")
 

pandas/_libs/tslibs/nattype.pyx

@@ -841,7 +841,7 @@ class NaTType(_NaT):
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for time which Timestamp will be converted to.
             None will remove timezone holding UTC time.
 
@@ -894,7 +894,7 @@ class NaTType(_NaT):
         ----------
         ordinal : int
             Date corresponding to a proleptic Gregorian ordinal.
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for the Timestamp.
 
         Notes
@@ -1307,7 +1307,7 @@ timedelta}, default 'raise'
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for time which Timestamp will be converted to.
             None will remove timezone holding UTC time.
 
@@ -1361,7 +1361,7 @@ timedelta}, default 'raise'
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for time which Timestamp will be converted to.
             None will remove timezone holding local time.
 
@@ -1461,13 +1461,13 @@ default 'raise'
 
         Replace timezone (not a conversion):
 
-        >>> import pytz
-        >>> ts.replace(tzinfo=pytz.timezone('US/Pacific'))
+        >>> import zoneinfo
+        >>> ts.replace(tzinfo=zoneinfo.ZoneInfo('US/Pacific'))
         Timestamp('2020-03-14 15:32:52.192548651-0700', tz='US/Pacific')
 
         Analogous for ``pd.NaT``:
 
-        >>> pd.NaT.replace(tzinfo=pytz.timezone('US/Pacific'))
+        >>> pd.NaT.replace(tzinfo=zoneinfo.ZoneInfo('US/Pacific'))
         NaT
         """,
     )

pandas/_libs/tslibs/timestamps.pyx

@@ -1374,7 +1374,7 @@ class Timestamp(_Timestamp):
         Timezone info.
     nanosecond : int, optional, default 0
         Value of nanosecond.
-    tz : str, pytz.timezone, dateutil.tz.tzfile or None
+    tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
         Time zone for time which Timestamp will have.
     unit : str
         Unit used for conversion if ts_input is of type int or float. The
@@ -1446,7 +1446,7 @@ class Timestamp(_Timestamp):
         ----------
         ordinal : int
             Date corresponding to a proleptic Gregorian ordinal.
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for the Timestamp.
 
         Notes
@@ -2393,7 +2393,7 @@ timedelta}, default 'raise'
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for time which Timestamp will be converted to.
             None will remove timezone holding local time.
 
@@ -2500,7 +2500,7 @@ default 'raise'
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile or None
             Time zone for time which Timestamp will be converted to.
             None will remove timezone holding UTC time.
 
@@ -2604,13 +2604,13 @@ default 'raise'
 
         Replace timezone (not a conversion):
 
-        >>> import pytz
-        >>> ts.replace(tzinfo=pytz.timezone('US/Pacific'))
+        >>> import zoneinfo
+        >>> ts.replace(tzinfo=zoneinfo.ZoneInfo('US/Pacific'))
         Timestamp('2020-03-14 15:32:52.192548651-0700', tz='US/Pacific')
 
         Analogous for ``pd.NaT``:
 
-        >>> pd.NaT.replace(tzinfo=pytz.timezone('US/Pacific'))
+        >>> pd.NaT.replace(tzinfo=zoneinfo.ZoneInfo('US/Pacific'))
         NaT
         """
 

pandas/_libs/tslibs/timezones.pyx

@@ -119,27 +119,26 @@ cpdef inline object get_timezone(tzinfo tz):
         raise TypeError("tz argument cannot be None")
     if is_utc(tz):
         return tz
+    elif is_zoneinfo(tz):
+        return tz.key
+    elif treat_tz_as_pytz(tz):
+        zone = tz.zone
+        if zone is None:
+            return tz
+        return zone
+    elif treat_tz_as_dateutil(tz):
+        if ".tar.gz" in tz._filename:
+            raise ValueError(
+                "Bad tz filename. Dateutil on python 3 on windows has a "
+                "bug which causes tzfile._filename to be the same for all "
+                "timezone files. Please construct dateutil timezones "
+                'implicitly by passing a string like "dateutil/Europe'
+                '/London" when you construct your pandas objects instead '
+                "of passing a timezone object. See "
+                "https://github.com/pandas-dev/pandas/pull/7362")
+        return "dateutil/" + tz._filename
     else:
-        if treat_tz_as_dateutil(tz):
-            if ".tar.gz" in tz._filename:
-                raise ValueError(
-                    "Bad tz filename. Dateutil on python 3 on windows has a "
-                    "bug which causes tzfile._filename to be the same for all "
-                    "timezone files. Please construct dateutil timezones "
-                    'implicitly by passing a string like "dateutil/Europe'
-                    '/London" when you construct your pandas objects instead '
-                    "of passing a timezone object. See "
-                    "https://github.com/pandas-dev/pandas/pull/7362")
-            return "dateutil/" + tz._filename
-        else:
-            # tz is a pytz timezone or unknown.
-            try:
-                zone = tz.zone
-                if zone is None:
-                    return tz
-                return zone
-            except AttributeError:
-                return tz
+        return tz
 
 
 cpdef inline tzinfo maybe_get_tz(object tz):

pandas/_testing/_hypothesis.py

@@ -6,7 +6,6 @@
 
 from hypothesis import strategies as st
 from hypothesis.extra.dateutil import timezones as dateutil_timezones
-from hypothesis.extra.pytz import timezones as pytz_timezones
 
 from pandas.compat import is_platform_windows
 
@@ -57,7 +56,7 @@
 DATETIME_JAN_1_1900_OPTIONAL_TZ = st.datetimes(
     min_value=pd.Timestamp(1900, 1, 1).to_pydatetime(),  # pyright: ignore[reportArgumentType]
     max_value=pd.Timestamp(1900, 1, 1).to_pydatetime(),  # pyright: ignore[reportArgumentType]
-    timezones=st.one_of(st.none(), dateutil_timezones(), pytz_timezones()),
+    timezones=st.one_of(st.none(), dateutil_timezones(), st.timezones()),
 )
 
 DATETIME_IN_PD_TIMESTAMP_RANGE_NO_TZ = st.datetimes(

pandas/core/arrays/datetimes.py

@@ -594,7 +594,7 @@ def tz(self) -> tzinfo | None:
 
         Returns
         -------
-        datetime.tzinfo, pytz.tzinfo.BaseTZInfo, dateutil.tz.tz.tzfile, or None
+        zoneinfo.ZoneInfo,, datetime.tzinfo, pytz.tzinfo.BaseTZInfo, dateutil.tz.tz.tzfile, or None
             Returns None when the array is tz-naive.
 
         See Also
@@ -624,7 +624,7 @@ def tz(self) -> tzinfo | None:
         ... )
         >>> idx.tz
         datetime.timezone.utc
-        """
+        """  # noqa: E501
         # GH 18595
         return getattr(self.dtype, "tz", None)
 
@@ -863,7 +863,7 @@ def tz_convert(self, tz) -> Self:
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile, datetime.tzinfo or None
+        tz : str, zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile, datetime.tzinfo or None
             Time zone for time. Corresponding timestamps would be converted
             to this time zone of the Datetime Array/Index. A `tz` of None will
             convert to UTC and remove the timezone information.
@@ -923,7 +923,7 @@ def tz_convert(self, tz) -> Self:
                        '2014-08-01 08:00:00',
                        '2014-08-01 09:00:00'],
                         dtype='datetime64[ns]', freq='h')
-        """
+        """  # noqa: E501
         tz = timezones.maybe_get_tz(tz)
 
         if self.tz is None:
@@ -955,7 +955,7 @@ def tz_localize(
 
         Parameters
         ----------
-        tz : str, pytz.timezone, dateutil.tz.tzfile, datetime.tzinfo or None
+        tz : str, zoneinfo.ZoneInfo,, pytz.timezone, dateutil.tz.tzfile, datetime.tzinfo or None
             Time zone to convert timestamps to. Passing ``None`` will
             remove the time zone information preserving local time.
         ambiguous : 'infer', 'NaT', bool array, default 'raise'
@@ -1081,7 +1081,7 @@ def tz_localize(
         0   2015-03-29 03:30:00+02:00
         1   2015-03-29 03:30:00+02:00
         dtype: datetime64[ns, Europe/Warsaw]
-        """
+        """  # noqa: E501
         nonexistent_options = ("raise", "NaT", "shift_forward", "shift_backward")
         if nonexistent not in nonexistent_options and not isinstance(
             nonexistent, timedelta

pandas/core/indexes/datetimes.py

@@ -147,7 +147,7 @@ class DatetimeIndex(DatetimeTimedeltaMixin):
         One of pandas date offset strings or corresponding objects. The string
         'infer' can be passed in order to set the frequency of the index as the
         inferred frequency upon creation.
-    tz : pytz.timezone or dateutil.tz.tzfile or datetime.tzinfo or str
+    tz : zoneinfo.ZoneInfo, pytz.timezone, dateutil.tz.tzfile, datetime.tzinfo or str
         Set the Timezone of the data.
     ambiguous : 'infer', bool-ndarray, 'NaT', default 'raise'
         When clocks moved backward due to DST, ambiguous times may arise.