refactor: deprecate pytz in favor of builtin zoneinfo

docs/sphinx/source/user_guide/modeling_topics/timetimezones.rst

@@ -5,7 +5,7 @@ Time and time zones
 
 Dealing with time and time zones can be a frustrating experience in any
 programming language and for any application. pvlib-python relies on
-:py:mod:`pandas` and `pytz <http://pythonhosted.org/pytz/>`_ to handle
+:py:mod:`pandas` and the builtin :py:mod:`python:zoneinfo` to handle
 time and time zones. Therefore, the vast majority of the information in
 this document applies to any time series analysis using pandas and is
 not specific to pvlib-python.
@@ -27,39 +27,41 @@ time and time zone functionality in python and pvlib.
 .. ipython:: python
 
     import datetime
+    import zoneinfo
     import pandas as pd
-    import pytz
 
 
 Finding a time zone
 *******************
 
-pytz is based on the Olson time zone database. You can obtain a list of
-all valid time zone strings with ``pytz.all_timezones``. It's a long
-list, so we only print every 20th time zone.
+``zoneinfo`` is based on the IANA (Olson) time zone database. You can obtain
+a set of all valid time zone strings with ``zoneinfo.available_timezones()``.
+It's a large set, so we only print every 20th time zone (sorted for
+consistency).
 
 .. ipython:: python
 
-    len(pytz.all_timezones)
-    pytz.all_timezones[::20]
+    len(zoneinfo.available_timezones())
+    sorted(zoneinfo.available_timezones())[::20]
 
 Wikipedia's `List of tz database time zones
 <https://en.wikipedia.org/wiki/List_of_tz_database_time_zones>`_ is also
 good reference.
 
-The ``pytz.country_timezones`` function is useful, too.
+You can filter the available time zones using Python's built-in
+:py:func:`python:filter` function.
 
 .. ipython:: python
 
-    pytz.country_timezones('US')
+    sorted(filter(lambda x: 'America' in x, zoneinfo.available_timezones()))
 
-And don't forget about Python's :py:func:`python:filter` function.
+And you can also filter for GMT-based fixed offset zones:
 
 .. ipython:: python
 
-    list(filter(lambda x: 'GMT' in x, pytz.all_timezones))
+    sorted(filter(lambda x: 'GMT' in x, zoneinfo.available_timezones()))
 
-Note that while pytz has ``'EST'`` and ``'MST'``, it does not have
+Note that while the IANA database has ``'EST'`` and ``'MST'``, it does not have
 ``'PST'``. Use ``'Etc/GMT+8'`` instead, or see :ref:`fixedoffsets`.
 
 Timestamps
@@ -125,7 +127,7 @@ vs. the UTC offset in summer...
     pd.Timestamp('2015-6-1 00:00').tz_localize('US/Mountain')
     pd.Timestamp('2015-6-1 00:00').tz_localize('Etc/GMT+7')
 
-pandas and pytz make this time zone handling possible because pandas
+pandas makes this time zone handling possible because pandas
 stores all times as integer nanoseconds since January 1, 1970.
 Here is the pandas time representation of the integers 1 and 1e9.
 
@@ -174,12 +176,13 @@ specifications, but watch out for the counter-intuitive sign convention.
 
     pd.Timestamp('2015-1-1 00:00', tz='Etc/GMT-2')
 
-Fixed offset time zones can also be specified as offset minutes
-from UTC using ``pytz.FixedOffset``.
+Fixed offset time zones can also be specified using
+:py:class:`python:datetime.timezone` with a
+:py:class:`python:datetime.timedelta` offset.
 
 .. ipython:: python
 
-    pd.Timestamp('2015-1-1 00:00', tz=pytz.FixedOffset(120))
+    pd.Timestamp('2015-1-1 00:00', tz=datetime.timezone(datetime.timedelta(hours=2)))
 
 You can also specify the fixed offset directly in the ``tz_localize``
 method, however, be aware that this is not documented and that the
@@ -216,8 +219,8 @@ expected.
     # tz naive pandas Timestamp object
     pd.Timestamp(naive_python_dt)
 
-    # tz aware python datetime.datetime object
-    aware_python_dt = pytz.timezone('US/Mountain').localize(naive_python_dt)
+    # tz aware python datetime.datetime object using zoneinfo
+    aware_python_dt = naive_python_dt.replace(tzinfo=zoneinfo.ZoneInfo('US/Mountain'))
 
     # tz aware pandas Timestamp object
     pd.Timestamp(aware_python_dt)
@@ -234,13 +237,14 @@ passed to ``Timestamp``.
     # tz naive pandas Timestamp object (time=midnight)
     pd.Timestamp(naive_python_date)
 
-You cannot localize a native Python date object.
+You cannot localize a native Python date object directly; you must first
+convert it to a :py:class:`python:datetime.datetime`.
 
 .. ipython:: python
    :okexcept:
 
-    # fail
-    pytz.timezone('US/Mountain').localize(naive_python_date)
+    # fail: datetime.date has no tzinfo support via replace
+    naive_python_date.replace(tzinfo=zoneinfo.ZoneInfo('US/Mountain'))
 
 
 pvlib-specific functionality
@@ -348,7 +352,7 @@ UTC, and then convert it to the desired time zone.
 
 .. ipython:: python
 
-    fixed_tz = pytz.FixedOffset(tmy3_metadata['TZ'] * 60)
+    fixed_tz = datetime.timezone(datetime.timedelta(hours=tmy3_metadata['TZ']))
     solar_position_hack = solar_position_notz.tz_localize('UTC').tz_convert(fixed_tz)
 
     solar_position_hack.index

docs/sphinx/source/whatsnew/v0.15.2.rst

@@ -10,6 +10,8 @@ Breaking Changes
 
 Deprecations
 ~~~~~~~~~~~~
+* :py:attr:`pvlib.location.Location.pytz` is deprecated and will be removed in a future release. Use :py:attr:`~pvlib.location.Location.tz` instead.
+  (:issue:`2343`, :pull:`2757`)
 
 
 Bug fixes
@@ -62,3 +64,5 @@ Contributors
 * Cliff Hansen (:ghuser:`cwhanse`)
 * Arthur Onno (:ghuser:`ArthurOnnoTerabase`)
 * Adam R. Jensen (:ghuser:`AdamRJensen`)
+* :ghuser:`JoLo90`
+

docs/tutorials/solarposition.ipynb

@@ -121,7 +121,7 @@
    "outputs": [],
    "source": [
     "times = pd.date_range(start=datetime.datetime(2014,6,23), end=datetime.datetime(2014,6,24), freq='1Min')\n",
-    "times_loc = times.tz_localize(tus.pytz)"
+    "times_loc = times.tz_localize(tus.tz)"
    ]
   },
   {

pvlib/iotools/pvgis.py

@@ -20,7 +20,7 @@
 import requests
 import numpy as np
 import pandas as pd
-import pytz
+import zoneinfo
 from pvlib.iotools import read_epw
 
 URL = 'https://re.jrc.ec.europa.eu/api/'
@@ -413,10 +413,10 @@ def _coerce_and_roll_tmy(tmy_data, tz, year):
     re-interpreted as zero / UTC.
     """
     if tz:
-        tzname = pytz.timezone(f'Etc/GMT{-tz:+d}')
+        tzname = zoneinfo.ZoneInfo(f'Etc/GMT{-tz:+d}')  # noqa: E231
     else:
         tz = 0
-        tzname = pytz.timezone('UTC')
+        tzname = zoneinfo.ZoneInfo('UTC')
     new_index = pd.DatetimeIndex([
         timestamp.replace(year=year, tzinfo=tzname)
         for timestamp in tmy_data.index],

pvlib/location.py

@@ -14,6 +14,7 @@
 
 from pvlib import solarposition, clearsky, atmosphere, irradiance
 from pvlib.tools import _degrees_to_index
+from pvlib._deprecation import warn_deprecated
 
 
 class Location:
@@ -22,13 +23,11 @@ class Location:
     time zone, and altitude data associated with a particular geographic
     location. You can also assign a name to a location object.
 
-    Location objects have two time-zone attributes:
+    Location objects have a time-zone attribute ``tz`` (IANA timezone string).
 
-        * ``tz`` is an IANA time-zone string.
-        * ``pytz`` is a pytz-based time-zone object (read only).
+    .. deprecated:: 0.15.2
 
-    The read-only ``pytz`` attribute will stay in sync with any changes made
-    using ``tz``.
+       The ``pytz`` attribute is deprecated. Use ``tz`` instead.
 
     Location objects support the print method.
 
@@ -44,11 +43,11 @@ class Location:
 
     tz : time zone as str, int, float, or datetime.tzinfo, default 'UTC'.
         See http://en.wikipedia.org/wiki/List_of_tz_database_time_zones for a
-        list of valid name strings. An `int` or `float` must be a whole-number
-        hour offsets from UTC that can be converted to the IANA-supported
-        'Etc/GMT-N' format. (Note the limited range of the offset N and its
-        sign-change convention.) Time zones from the pytz and zoneinfo packages
-        may also be passed here, as they are subclasses of datetime.tzinfo.
+        list of valid name strings. An ``int`` or ``float`` must be a
+        whole-number hour offsets from UTC that can be converted to the
+        IANA-supported 'Etc/GMT-N' format. (Note the limited range of the
+        offset N and its sign-change convention.) Time zones from the
+        ``zoneinfo`` packages may also be passed.
 
         The `tz` attribute is represented as a valid IANA time zone name
         string.
@@ -108,17 +107,19 @@ def tz(self, tz_):
         if isinstance(tz_, str):
             self._zoneinfo = zoneinfo.ZoneInfo(tz_)
         elif isinstance(tz_, int):
-            self._zoneinfo = zoneinfo.ZoneInfo(f"Etc/GMT{-tz_:+d}")
+            tz_str = f"Etc/GMT{-tz_:+d}"  # noqa: E231
+            self._zoneinfo = zoneinfo.ZoneInfo(tz_str)
         elif isinstance(tz_, float):
             if tz_ % 1 != 0:
                 raise TypeError(
                     "Floating-point tz has non-zero fractional part: "
                     f"{tz_}. Only whole-number offsets are supported."
                 )
 
-            self._zoneinfo = zoneinfo.ZoneInfo(f"Etc/GMT{-int(tz_):+d}")
+            tz_str = f"Etc/GMT{-int(tz_):+d}"  # noqa: E231
+            self._zoneinfo = zoneinfo.ZoneInfo(tz_str)
         elif isinstance(tz_, datetime.tzinfo):
-            # Includes time zones generated by pytz and zoneinfo packages.
+            # Includes time zones generated by zoneinfo packages.
             self._zoneinfo = zoneinfo.ZoneInfo(str(tz_))
         else:
             raise TypeError(
@@ -128,8 +129,20 @@ def tz(self, tz_):
             )
 
     @property
-    def pytz(self):
-        """The location's pytz time zone (read only)."""
+    def pytz(self):  # pragma: no cover
+        """The location's pytz time zone (read only).
+
+        .. deprecated:: 0.15.2
+            The ``pytz`` attribute is deprecated. Use the ``tz`` property
+            instead.
+        """
+        warn_deprecated(
+            since='0.15.2',
+            removal='0.17.0',
+            name='pytz',
+            obj_type='attribute',
+            alternative='tz',
+        )
         return pytz.timezone(str(self._zoneinfo))
 
     @classmethod

pvlib/solarposition.py

@@ -1360,11 +1360,11 @@ def hour_angle(times, longitude, equation_of_time):
         Corresponding timestamps, must be localized to the timezone for the
         ``longitude``.
 
-        A `pytz.exceptions.AmbiguousTimeError` will be raised if any of the
-        given times are on a day when the local daylight savings transition
-        happens at midnight.  If you're working with such a timezone,
-        consider converting to a non-DST timezone (e.g. GMT-4) before
-        calling this function.
+        ``AmbiguousTimeError`` in ``pandas<3``, ``ValueError`` in ``pandas>=3``
+        will be raised if any of the given times are on a day when the local
+        daylight savings transition happens at midnight.  If you're working
+        with such a timezone, consider converting to a non-DST timezone
+        (e.g. GMT-4) before calling this function.
     longitude : numeric
         Longitude in degrees
     equation_of_time : numeric

pvlib/tools.py

@@ -4,11 +4,12 @@
 
 import contextlib
 import datetime as dt
+from datetime import timezone
 import warnings
 
 import numpy as np
 import pandas as pd
-import pytz
+import zoneinfo
 
 
 def cosd(angle):
@@ -135,8 +136,8 @@ def localize_to_utc(time, location):
     """
     if isinstance(time, dt.datetime):
         if time.tzinfo is None:
-            time = location.pytz.localize(time)
-        time_utc = time.astimezone(pytz.utc)
+            time = time.replace(tzinfo=zoneinfo.ZoneInfo(location.tz))
+        time_utc = time.astimezone(timezone.utc)
     else:
         try:
             time_utc = time.tz_convert('UTC')
@@ -162,11 +163,11 @@ def datetime_to_djd(time):
     """
 
     if time.tzinfo is None:
-        time_utc = pytz.utc.localize(time)
+        time_utc = time.replace(tzinfo=timezone.utc)
     else:
-        time_utc = time.astimezone(pytz.utc)
+        time_utc = time.astimezone(timezone.utc)
 
-    djd_start = pytz.utc.localize(dt.datetime(1899, 12, 31, 12))
+    djd_start = dt.datetime(1899, 12, 31, 12, tzinfo=timezone.utc)
     djd = (time_utc - djd_start).total_seconds() * 1.0/(60 * 60 * 24)
 
     return djd
@@ -189,10 +190,10 @@ def djd_to_datetime(djd, tz='UTC'):
        The resultant datetime localized to tz
     """
 
-    djd_start = pytz.utc.localize(dt.datetime(1899, 12, 31, 12))
+    djd_start = dt.datetime(1899, 12, 31, 12, tzinfo=timezone.utc)
 
     utc_time = djd_start + dt.timedelta(days=djd)
-    return utc_time.astimezone(pytz.timezone(tz))
+    return utc_time.astimezone(zoneinfo.ZoneInfo(tz))
 
 
 def _pandas_to_doy(pd_object):

tests/iotools/test_midc.py

@@ -1,6 +1,5 @@
 import pandas as pd
 import pytest
-import pytz
 
 from pvlib.iotools import midc
 from tests.conftest import TESTS_DATA_DIR, RERUNS, RERUNS_DELAY

tests/test_clearsky.py

@@ -3,7 +3,7 @@
 import numpy as np
 from numpy import nan
 import pandas as pd
-import pytz
+import zoneinfo
 from scipy.linalg import hankel
 
 import pytest
@@ -770,7 +770,7 @@ def test_bird():
     times = pd.date_range(start='1/1/2015 0:00', end='12/31/2015 23:00',
                           freq='h')
     tz = -7  # test timezone
-    gmt_tz = pytz.timezone('Etc/GMT%+d' % -(tz))
+    gmt_tz = zoneinfo.ZoneInfo(f'Etc/GMT{-tz:+d}')  # noqa: E231
     times = times.tz_localize(gmt_tz)  # set timezone
     times_utc = times.tz_convert('UTC')
     # match test data from BIRD_08_16_2012.xls