Make pytz an optional dependency

mroeschke · mroeschke · commit 51dfbe708fa9 · 2024-06-24T14:10:05.000-07:00
diff --git a/.circleci/config.yml b/.circleci/config.yml
@@ -54,7 +54,7 @@ jobs:
             /opt/python/cp311-cp311/bin/python -m venv ~/virtualenvs/pandas-dev
             . ~/virtualenvs/pandas-dev/bin/activate
             python -m pip install --no-cache-dir -U pip wheel setuptools meson-python==0.13.1 meson[ninja]==1.2.1
-            python -m pip install --no-cache-dir versioneer[toml] cython numpy python-dateutil pytz pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
+            python -m pip install --no-cache-dir versioneer[toml] cython numpy python-dateutil pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
             python -m pip install --no-cache-dir --no-build-isolation -e . --config-settings=setup-args="--werror"
             python -m pip list --no-cache-dir
             export PANDAS_CI=1
diff --git a/.github/workflows/unit-tests.yml b/.github/workflows/unit-tests.yml
@@ -230,7 +230,7 @@ jobs:
           . ~/virtualenvs/pandas-dev/bin/activate
           python -m pip install --no-cache-dir -U pip wheel setuptools meson[ninja]==1.2.1 meson-python==0.13.1
           python -m pip install numpy --config-settings=setup-args="-Dallow-noblas=true"
-          python -m pip install --no-cache-dir versioneer[toml] cython python-dateutil pytz pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
+          python -m pip install --no-cache-dir versioneer[toml] cython python-dateutil pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
           python -m pip install --no-cache-dir --no-build-isolation -e . --config-settings=setup-args="--werror"
           python -m pip list --no-cache-dir
           export PANDAS_CI=1
@@ -268,7 +268,7 @@ jobs:
           /opt/python/cp311-cp311/bin/python -m venv ~/virtualenvs/pandas-dev
           . ~/virtualenvs/pandas-dev/bin/activate
           python -m pip install --no-cache-dir -U pip wheel setuptools meson-python==0.13.1 meson[ninja]==1.2.1
-          python -m pip install --no-cache-dir versioneer[toml] cython numpy python-dateutil pytz pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
+          python -m pip install --no-cache-dir versioneer[toml] cython numpy python-dateutil pytest>=7.3.2 pytest-xdist>=2.2.0 hypothesis>=6.46.1
           python -m pip install --no-cache-dir --no-build-isolation -e . --config-settings=setup-args="--werror"
           python -m pip list --no-cache-dir
 
@@ -289,7 +289,7 @@ jobs:
     # In general, this will remain frozen(present, but not running) until:
     #    - The next unreleased Python version has released beta 1
     #      - This version should be available on GitHub Actions.
-    #    - Our required build/runtime dependencies(numpy, pytz, Cython, python-dateutil)
+    #    - Our required build/runtime dependencies(numpy, Cython, python-dateutil)
     #      support that unreleased Python version.
     #    To unfreeze, comment out the ``if: false`` condition, and make sure you update
     #    the name of the workflow and Python version in actions/setup-python ``python-version:``
@@ -342,7 +342,7 @@ jobs:
           python -m pip install --upgrade pip setuptools wheel meson[ninja]==1.2.1 meson-python==0.13.1
           python -m pip install --pre --extra-index-url https://pypi.anaconda.org/scientific-python-nightly-wheels/simple numpy
           python -m pip install versioneer[toml]
-          python -m pip install python-dateutil pytz tzdata cython hypothesis>=6.46.1 pytest>=7.3.2 pytest-xdist>=2.2.0 pytest-cov
+          python -m pip install python-dateutil tzdata cython hypothesis>=6.46.1 pytest>=7.3.2 pytest-xdist>=2.2.0 pytest-cov
           python -m pip install -ve . --no-build-isolation --no-index --no-deps --config-settings=setup-args="--werror"
           python -m pip list
 
diff --git a/ci/deps/actions-310-minimum_versions.yaml b/ci/deps/actions-310-minimum_versions.yaml
@@ -23,7 +23,6 @@ dependencies:
   # required dependencies
   - python-dateutil=2.8.2
   - numpy=1.23.5
-  - pytz=2020.1
 
   # optional dependencies
   - beautifulsoup4=4.11.2
@@ -49,6 +48,7 @@ dependencies:
   - pyreadstat=1.2.0
   - pytables=3.8.0
   - python-calamine=0.1.7
+  - pytz=2023.4
   - pyxlsb=1.0.10
   - s3fs=2022.11.0
   - scipy=1.10.0
diff --git a/ci/deps/actions-310.yaml b/ci/deps/actions-310.yaml
@@ -20,7 +20,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -46,6 +45,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/ci/deps/actions-311-downstream_compat.yaml b/ci/deps/actions-311-downstream_compat.yaml
@@ -22,7 +22,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -48,6 +47,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/ci/deps/actions-311-numpydev.yaml b/ci/deps/actions-311-numpydev.yaml
@@ -18,7 +18,6 @@ dependencies:
 
   # pandas dependencies
   - python-dateutil
-  - pytz
   - pip
 
   - pip:
diff --git a/ci/deps/actions-311-pyarrownightly.yaml b/ci/deps/actions-311-pyarrownightly.yaml
@@ -19,7 +19,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy<2
-  - pytz
   - pip
 
   - pip:
diff --git a/ci/deps/actions-311.yaml b/ci/deps/actions-311.yaml
@@ -20,7 +20,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -46,6 +45,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/ci/deps/actions-312.yaml b/ci/deps/actions-312.yaml
@@ -20,7 +20,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -46,6 +45,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/ci/deps/actions-pypy-39.yaml b/ci/deps/actions-pypy-39.yaml
@@ -22,6 +22,5 @@ dependencies:
   # required
   - numpy
   - python-dateutil
-  - pytz
   - pip:
     - tzdata>=2022.7
diff --git a/ci/deps/circle-311-arm64.yaml b/ci/deps/circle-311-arm64.yaml
@@ -21,7 +21,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -47,6 +46,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/ci/meta.yaml b/ci/meta.yaml
@@ -37,7 +37,6 @@ requirements:
     - numpy >=1.21.6  # [py<311]
     - numpy >=1.23.2  # [py>=311]
     - python-dateutil >=2.8.2
-    - pytz >=2020.1
     - python-tzdata >=2022.7
 
 test:
diff --git a/doc/source/getting_started/install.rst b/doc/source/getting_started/install.rst
@@ -205,7 +205,6 @@ Package                                                          Minimum support
 ================================================================ ==========================
 `NumPy <https://numpy.org>`__                                    1.23.5
 `python-dateutil <https://dateutil.readthedocs.io/en/stable/>`__ 2.8.2
-`pytz <https://pypi.org/project/pytz/>`__                        2020.1
 `tzdata <https://pypi.org/project/tzdata/>`__                    2022.7
 ================================================================ ==========================
 
@@ -419,3 +418,14 @@ Dependency                Minimum Version    pip extra       Notes
 ========================= ================== =============== =============================================================
 Zstandard                 0.19.0             compression     Zstandard compression
 ========================= ================== =============== =============================================================
+
+Timezone
+^^^^^^^^
+
+Installable with ``pip install "pandas[timezone]"``
+
+========================= ================== =================== =============================================================
+Dependency                Minimum Version    pip extra           Notes
+========================= ================== =================== =============================================================
+pytz                      2023.3             timezone            Alternative timezone library to ``zoneinfo``.
+========================= ================== =================== =============================================================
diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
@@ -213,6 +213,8 @@ Optional libraries below the lowest tested version may still work, but are not c
 +------------------------+---------------------+
 | Package                | New Minimum Version |
 +========================+=====================+
+| pytz                   | 2023.4              |
++------------------------+---------------------+
 | fastparquet            | 2023.10.0           |
 +------------------------+---------------------+
 | adbc-driver-postgresql | 0.10.0              |
@@ -222,6 +224,35 @@ Optional libraries below the lowest tested version may still work, but are not c
 
 See :ref:`install.dependencies` and :ref:`install.optional_dependencies` for more.
 
+.. _whatsnew_300.api_breaking.pytz:
+
+``pytz`` now an optional dependency
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+pandas now uses :py:mod:`zoneinfo` from the standard library as the default timezone implementation when passing a timezone
+string to various methods. (:issue:`34916`)
+
+*Old behavior:*
+
+.. code-block:: ipython
+    In [1]: ts = pd.Timestamp(2024, 1, 1).tz_localize("US/Pacific")
+    In [2]: ts.tz
+    <DstTzInfo 'US/Pacific' LMT-1 day, 16:07:00 STD>
+
+*New behavior:*
+
+.. ipython:: python
+    ts = pd.Timestamp(2024, 1, 1).tz_localize("US/Pacific")
+    ts.tz
+
+``pytz`` timezone objects are still supported when passed directly, but they will no longer be returned by default
+from string inputs. Moreover, ``pytz`` is no longer a required dependency of pandas, but can be installed
+with the pip extra ``pip install pandas[timezone]``.
+
+
+Additionally, pandas no longer throws ``pytz`` exceptions for timezone operations leading to ambiguous or nonexistent
+times. These operations will now yield
+
 .. _whatsnew_300.api_breaking.other:
 
 Other API changes
diff --git a/environment.yml b/environment.yml
@@ -24,7 +24,6 @@ dependencies:
   # required dependencies
   - python-dateutil
   - numpy<2
-  - pytz
 
   # optional dependencies
   - beautifulsoup4>=4.11.2
@@ -50,6 +49,7 @@ dependencies:
   - pyreadstat>=1.2.0
   - pytables>=3.8.0
   - python-calamine>=0.1.7
+  - pytz>=2023.4
   - pyxlsb>=1.0.10
   - s3fs>=2022.11.0
   - scipy>=1.10.0
diff --git a/pandas/__init__.py b/pandas/__init__.py
@@ -3,7 +3,7 @@
 __docformat__ = "restructuredtext"
 
 # Let users know if they're missing any of our hard dependencies
-_hard_dependencies = ("numpy", "pytz", "dateutil")
+_hard_dependencies = ("numpy", "dateutil")
 _missing_dependencies = []
 
 for _dependency in _hard_dependencies:
diff --git a/pandas/_libs/tslibs/conversion.pyx b/pandas/_libs/tslibs/conversion.pyx
@@ -69,6 +69,7 @@ from pandas._libs.tslibs.timestamps cimport _Timestamp
 from pandas._libs.tslibs.timezones cimport (
     get_utcoffset,
     is_utc,
+    treat_tz_as_pytz,
 )
 from pandas._libs.tslibs.tzconversion cimport (
     Localizer,
@@ -742,11 +743,11 @@ cdef datetime _localize_pydatetime(datetime dt, tzinfo tz):
         identically, i.e. discards nanos from Timestamps.
         It also assumes that the `tz` input is not None.
     """
-    try:
+    if treat_tz_as_pytz(tz):
         # datetime.replace with pytz may be incorrect result
         # TODO: try to respect `fold` attribute
         return tz.localize(dt, is_dst=None)
-    except AttributeError:
+    else:
         return dt.replace(tzinfo=tz)
 
 
diff --git a/pandas/_libs/tslibs/strptime.pyx b/pandas/_libs/tslibs/strptime.pyx
@@ -16,6 +16,7 @@ FUNCTIONS:
     strptime -- Calculates the time struct represented by the passed-in string
 """
 from datetime import timezone
+import zoneinfo
 
 from cpython.datetime cimport (
     PyDate_Check,
@@ -38,7 +39,6 @@ from _thread import allocate_lock as _thread_allocate_lock
 import re
 
 import numpy as np
-import pytz
 
 cimport numpy as cnp
 from numpy cimport (
@@ -747,7 +747,7 @@ cdef tzinfo _parse_with_format(
                 week_of_year_start = 0
         elif parse_code == 17:
             # e.g. val='2011-12-30T00:00:00.000000UTC'; fmt='%Y-%m-%dT%H:%M:%S.%f%Z'
-            tz = pytz.timezone(found_dict["Z"])
+            tz = zoneinfo.ZoneInfo(found_dict["Z"])
         elif parse_code == 19:
             # e.g. val='March 1, 2018 12:00:00+0400'; fmt='%B %d, %Y %H:%M:%S%z'
             tz = parse_timezone_directive(found_dict["z"])
@@ -837,7 +837,7 @@ class TimeRE(_TimeRE):
         if key == "Z":
             # lazy computation
             if self._Z is None:
-                self._Z = self.__seqToRE(pytz.all_timezones, "Z")
+                self._Z = self.__seqToRE(zoneinfo.available_timezones(), "Z")
             # Note: handling Z is the key difference vs using the stdlib
             # _strptime.TimeRE. test_to_datetime_parse_tzname_or_tzoffset with
             # fmt='%Y-%m-%d %H:%M:%S %Z' fails with the stdlib version.
diff --git a/pandas/_libs/tslibs/timezones.pyx b/pandas/_libs/tslibs/timezones.pyx
diff --git a/pandas/_libs/tslibs/tzconversion.pyx b/pandas/_libs/tslibs/tzconversion.pyx
diff --git a/pandas/compat/_optional.py b/pandas/compat/_optional.py
diff --git a/pandas/core/dtypes/dtypes.py b/pandas/core/dtypes/dtypes.py
diff --git a/pandas/io/json/_table_schema.py b/pandas/io/json/_table_schema.py
diff --git a/pandas/util/_print_versions.py b/pandas/util/_print_versions.py
diff --git a/pyproject.toml b/pyproject.toml
diff --git a/requirements-dev.txt b/requirements-dev.txt
