refactor: deprecate pytz in favor of builtin zoneinfo

Author: JoLo90

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

@@ -10,6 +10,8 @@ Breaking Changes
 
 Deprecations
 ~~~~~~~~~~~~
+* ``Location.pytz`` is deprecated. Use ``Location.tz`` instead.
+  (:ghuser:`JoLo90`, :pull:`2757`)
 
 
 Bug fixes

docs/tutorials/solarposition.ipynb

@@ -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/iotools/pvgis.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`` is an IANA time-zone string.
-        * ``pytz`` is a pytz-based time-zone object (read only).
 
-    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.
 
@@ -47,8 +46,8 @@ class Location:
         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.
+        sign-change convention.) Time zones from the zoneinfo packages may also
+        be passed here.
 
         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::
+            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/location.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.
+        An error (AmbiguousTimeError in older pandas, ValueError in newer)
+        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/solarposition.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=location._zoneinfo)
+        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):

pvlib/tools.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/iotools/test_midc.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

tests/test_clearsky.py

@@ -9,8 +9,6 @@
 
 import pytest
 
-import pytz
-
 import pvlib
 from pvlib import location
 from pvlib.location import Location, lookup_altitude
@@ -37,29 +35,26 @@ def test_location_all():
         pytest.param('Asia/Yangon', 'Asia/Yangon'),
         pytest.param(datetime.timezone.utc, 'UTC'),
         pytest.param(zoneinfo.ZoneInfo('Etc/GMT-7'), 'Etc/GMT-7'),
-        pytest.param(pytz.timezone('US/Arizona'), 'US/Arizona'),
+        pytest.param(zoneinfo.ZoneInfo('US/Arizona'), 'US/Arizona'),
         pytest.param(-6, 'Etc/GMT+6'),
         pytest.param(-11.0, 'Etc/GMT+11'),
         pytest.param(12, 'Etc/GMT-12'),
     ],
 )
 def test_location_tz(tz, tz_expected):
     loc = Location(32.2, -111, tz)
-    assert isinstance(loc.pytz, datetime.tzinfo)  # Abstract base class.
-    assert isinstance(loc.pytz, pytz.tzinfo.BaseTzInfo)
+    assert isinstance(loc._zoneinfo, datetime.tzinfo)  # Abstract base class.
     assert type(loc.tz) is str
     assert loc.tz == tz_expected
 
 
 def test_location_tz_update():
     loc = Location(32.2, -111, -11)
     assert loc.tz == 'Etc/GMT+11'
-    assert loc.pytz == pytz.timezone('Etc/GMT+11')  # Deprecated attribute.
 
     # Updating Location's tz updates read-only time-zone attributes.
     loc.tz = 7
     assert loc.tz == 'Etc/GMT-7'
-    assert loc.pytz == pytz.timezone('Etc/GMT-7')  # Deprecated attribute.
 
 
 @pytest.mark.parametrize(
@@ -99,8 +94,8 @@ def test_location_print_all():
     assert tus.__str__() == expected_str
 
 
-def test_location_print_pytz():
-    tus = Location(32.2, -111, pytz.timezone('US/Arizona'), 700, 'Tucson')
+def test_location_print():
+    tus = Location(32.2, -111, zoneinfo.ZoneInfo('US/Arizona'), 700, 'Tucson')
     expected_str = '\n'.join([
         'Location: ',
         '  name: Tucson',

tests/test_location.py

@@ -1,21 +1,20 @@
 import calendar
 import datetime
+import math
 import warnings
+import zoneinfo
+from datetime import timezone
 
 import numpy as np
 import pandas as pd
-
-from .conftest import assert_frame_equal, assert_series_equal
-from numpy.testing import assert_allclose
 import pytest
-import pytz
+from numpy.testing import assert_allclose
 
-from pvlib.location import Location
 from pvlib import solarposition, spa
+from pvlib.location import Location
 
-from .conftest import (
-    requires_ephem, requires_spa_c, requires_numba, requires_pandas_2_0
-)
+from .conftest import (assert_frame_equal, assert_series_equal, requires_ephem,
+                       requires_numba, requires_pandas_2_0, requires_spa_c)
 
 # setup times and locations to be tested.
 times = pd.date_range(start=datetime.datetime(2014, 6, 24),
@@ -343,29 +342,26 @@ def test_pyephem_physical_dst(expected_solpos, golden):
 
 @requires_ephem
 def test_calc_time():
-    import pytz
-    import math
     # validation from USNO solar position calculator online
 
-    epoch = datetime.datetime(1970, 1, 1)
-    epoch_dt = pytz.utc.localize(epoch)
+    epoch = datetime.datetime(1970, 1, 1, tzinfo=timezone.utc)
 
     loc = tus
     loc.pressure = 0
-    actual_time = pytz.timezone(loc.tz).localize(
-        datetime.datetime(2014, 10, 10, 8, 30))
-    lb = pytz.timezone(loc.tz).localize(datetime.datetime(2014, 10, 10, tol))
-    ub = pytz.timezone(loc.tz).localize(datetime.datetime(2014, 10, 10, 10))
+    tz = zoneinfo.ZoneInfo(loc.tz)
+    actual_time = datetime.datetime(2014, 10, 10, 8, 30, tzinfo=tz)
+    lb = datetime.datetime(2014, 10, 10, tol, tzinfo=tz)
+    ub = datetime.datetime(2014, 10, 10, 10, tzinfo=tz)
     alt = solarposition.calc_time(lb, ub, loc.latitude, loc.longitude,
                                   'alt', math.radians(24.7))
     az = solarposition.calc_time(lb, ub, loc.latitude, loc.longitude,
                                  'az', math.radians(116.3))
-    actual_timestamp = (actual_time - epoch_dt).total_seconds()
+    actual_timestamp = (actual_time - epoch).total_seconds()
 
     assert_allclose((alt.replace(second=0, microsecond=0) -
-                     epoch_dt).total_seconds(), actual_timestamp)
+                     epoch).total_seconds(), actual_timestamp)
     assert_allclose((az.replace(second=0, microsecond=0) -
-                     epoch_dt).total_seconds(), actual_timestamp)
+                     epoch).total_seconds(), actual_timestamp)
 
 
 @requires_ephem
@@ -715,6 +711,15 @@ def test_hour_angle_with_tricky_timezones():
     # GH 2132
     # tests timezones that have a DST shift at midnight
 
+    try:  # transitive dependency to pytz through pandas < 3
+        import pytz
+        _NonExistentTimeError = pytz.exceptions.NonExistentTimeError
+        _AmbiguousTimeError = pytz.exceptions.AmbiguousTimeError
+    except ImportError:  # pragma: no cover
+        # pandas 3.x dropped pytz; these are now raised as ValueError
+        _NonExistentTimeError = ValueError
+        _AmbiguousTimeError = ValueError
+
     eot = np.array([-3.935172, -4.117227, -4.026295, -4.026295])
 
     longitude = 70.6693
@@ -726,7 +731,7 @@ def test_hour_angle_with_tricky_timezones():
     ]).tz_localize('America/Santiago', nonexistent='shift_forward')
 
     with pytest.raises((
-        pytz.exceptions.NonExistentTimeError,  # pandas 1.x, 2.x
+        _NonExistentTimeError,  # pandas 1.x, 2.x
         ValueError,  # pandas 3.x
     )):
         times.normalize()
@@ -743,7 +748,7 @@ def test_hour_angle_with_tricky_timezones():
     ]).tz_localize('America/Havana', ambiguous=[True, True, False, False])
 
     with pytest.raises((
-        pytz.exceptions.AmbiguousTimeError,  # pandas 1.x, 2.x
+        _AmbiguousTimeError,  # pandas 1.x, 2.x
         ValueError,  # pandas 3.x
     )):
         solarposition.hour_angle(times, longitude, eot)