Add documentation of deprecation

doc/whats-new.rst

@@ -30,7 +30,10 @@ Breaking changes
 
 Deprecations
 ~~~~~~~~~~~~
-
+- Following pandas, the `closed` arguments of :py:func:`cftime_range` and
+  :py:func:`date_range` are deprecated in favor of the `inclusive` arguments,
+  and will be removed in a future version of xarray (:issue:`6985`:,
+  :pull:`7373`).  By `Spencer Clark <https://github.com/spencerkclark>`_.
 
 Bug fixes
 ~~~~~~~~~

xarray/coding/cftime_offsets.py

@@ -45,7 +45,7 @@
 from datetime import datetime, timedelta
 from enum import Enum
 from functools import partial
-from typing import ClassVar
+from typing import TYPE_CHECKING, ClassVar, Literal
 
 import numpy as np
 import pandas as pd
@@ -67,6 +67,10 @@
     cftime = None
 
 
+if TYPE_CHECKING:
+    from xarray.core.types import InclusiveOptions, SideOptions
+
+
 def get_date_type(calendar, use_cftime=True):
     """Return the cftime date type for a given calendar name."""
     if cftime is None:
@@ -852,15 +856,24 @@ def _generate_range(start, end, periods, offset):
 
 
 class _NoDefault(Enum):
-    """Used by pandas to specify a default value for a deprecated argument."""
+    """Used by pandas to specify a default value for a deprecated argument.
+    Copied from pandas._libs.lib._NoDefault.
+    """
 
     no_default = "NO_DEFAULT"
 
     def __repr__(self) -> str:
         return "<no_default>"
 
 
+no_default = (
+    _NoDefault.no_default
+)  # Sentinel indicating the default value following pandas
+NoDefault = Literal[_NoDefault.no_default]  # For typing following pandas
+
+
 def _translate_closed_to_inclusive(closed):
+    """Follows code added in pandas #43504."""
     emit_user_level_warning(
         "Following pandas, the `closed` argument is deprecated in "
         "favor of the `inclusive` argument, and will be removed in "
@@ -880,12 +893,13 @@ def _translate_closed_to_inclusive(closed):
 
 
 def _infer_inclusive(closed, inclusive):
-    if closed is not _NoDefault and inclusive is not None:
+    """Follows code added in pandas #43504."""
+    if closed is not no_default and inclusive is not None:
         raise ValueError(
-            "Deprecated argument `closed` cannot be passed if "
-            "argument `inclusive` is not None."
+            "Following pandas, deprecated argument `closed` cannot be "
+            "passed if argument `inclusive` is not None."
         )
-    if closed is not _NoDefault:
+    if closed is not no_default:
         inclusive = _translate_closed_to_inclusive(closed)
     elif inclusive is None:
         inclusive = "both"
@@ -899,8 +913,8 @@ def cftime_range(
     freq="D",
     normalize=False,
     name=None,
-    closed=_NoDefault,
-    inclusive=None,
+    closed: NoDefault | SideOptions = no_default,
+    inclusive: None | InclusiveOptions = None,
     calendar="standard",
 ):
     """Return a fixed frequency CFTimeIndex.
@@ -922,8 +936,15 @@ def cftime_range(
     closed : {"left", "right"} or None, default: _NoDefault
         Make the interval closed with respect to the given frequency to the
         "left", "right", or both sides (None).
+
+        .. deprecated:: 2023.01.1
+            Following pandas, the `closed` argument is deprecated in favor
+            of the `inclusive` argument, and will be removed in a future
+            version of xarray.
     inclusive : {None, "both", "neither", "left", "right"}, default None
-        Include boundaries; Whether to set each bound as closed or open.
+        Include boundaries; whether to set each bound as closed or open.
+
+        .. versionadded:: 2023.01.1
     calendar : str, default: "standard"
         Calendar type for the datetimes.
 
@@ -938,7 +959,6 @@ def cftime_range(
     features of ``pandas.date_range`` (e.g. specifying how the index is
     ``closed`` on either side, or whether or not to ``normalize`` the start and
     end bounds); however, there are some notable exceptions:
-
     - You cannot specify a ``tz`` (time zone) argument.
     - Start or end dates specified as partial-datetime strings must use the
       `ISO-8601 format <https://en.wikipedia.org/wiki/ISO_8601>`_.
@@ -1129,8 +1149,8 @@ def date_range(
     tz=None,
     normalize=False,
     name=None,
-    closed=_NoDefault,
-    inclusive=None,
+    closed: NoDefault | SideOptions = no_default,
+    inclusive: None | InclusiveOptions = None,
     calendar="standard",
     use_cftime=None,
 ):
@@ -1160,8 +1180,15 @@ def date_range(
     closed : {"left", "right"} or None, default: _NoDefault
         Make the interval closed with respect to the given frequency to the
         "left", "right", or both sides (None).
+
+        .. deprecated:: 2023.01.1
+            Following pandas, the `closed` argument is deprecated in favor
+            of the `inclusive` argument, and will be removed in a future
+            version of xarray.
     inclusive : {None, "both", "neither", "left", "right"}, default None
-        Include boundaries; Whether to set each bound as closed or open.
+        Include boundaries; whether to set each bound as closed or open.
+
+        .. versionadded:: 2023.01.1
     calendar : str, default: "standard"
         Calendar type for the datetimes.
     use_cftime : boolean, optional

xarray/core/types.py

@@ -172,6 +172,7 @@ def dtype(self) -> np.dtype:
 
 CoarsenBoundaryOptions = Literal["exact", "trim", "pad"]
 SideOptions = Literal["left", "right"]
+InclusiveOptions = Literal["both", "neither", "left", "right"]
 
 ScaleOptions = Literal["linear", "symlog", "log", "logit", None]
 HueStyleOptions = Literal["continuous", "discrete", None]

xarray/tests/test_cftime_offsets.py

@@ -1411,16 +1411,16 @@ def as_timedelta_not_implemented_error():
 
 
 @pytest.mark.parametrize("function", [cftime_range, date_range])
-def test_cftime_or_date_range_closed_and_inclusive_error(function):
+def test_cftime_or_date_range_closed_and_inclusive_error(function) -> None:
     if function == cftime_range and not has_cftime:
         pytest.skip("requires cftime")
 
-    with pytest.raises(ValueError, match="Deprecated argument `closed`"):
+    with pytest.raises(ValueError, match="Following pandas, deprecated"):
         function("2000", periods=3, closed=None, inclusive="right")
 
 
 @pytest.mark.parametrize("function", [cftime_range, date_range])
-def test_cftime_or_date_range_invalid_closed_value(function):
+def test_cftime_or_date_range_invalid_closed_value(function) -> None:
     if function == cftime_range and not has_cftime:
         pytest.skip("requires cftime")
 
@@ -1432,7 +1432,7 @@ def test_cftime_or_date_range_invalid_closed_value(function):
 @pytest.mark.parametrize(
     ("closed", "inclusive"), [(None, "both"), ("left", "left"), ("right", "right")]
 )
-def test_cftime_or_date_range_closed(function, closed, inclusive):
+def test_cftime_or_date_range_closed(function, closed, inclusive) -> None:
     if function == cftime_range and not has_cftime:
         pytest.skip("requires cftime")
 
@@ -1445,7 +1445,7 @@ def test_cftime_or_date_range_closed(function, closed, inclusive):
 
 
 @pytest.mark.parametrize("function", [cftime_range, date_range])
-def test_cftime_or_date_range_inclusive_None(function):
+def test_cftime_or_date_range_inclusive_None(function) -> None:
     if function == cftime_range and not has_cftime:
         pytest.skip("requires cftime")
 

xarray/tests/test_cftimeindex_resample.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 import datetime
+from typing import TypedDict
 
 import numpy as np
 import pandas as pd
@@ -189,6 +190,12 @@ def test_calendars(calendar) -> None:
     xr.testing.assert_identical(da_cftime, da_datetime)
 
 
+class DateRangeKwargs(TypedDict):
+    start: str
+    periods: int
+    freq: str
+
+
 @pytest.mark.parametrize("closed", ["left", "right"])
 @pytest.mark.parametrize(
     "origin",
@@ -198,7 +205,7 @@ def test_calendars(calendar) -> None:
 def test_origin(closed, origin) -> None:
     initial_freq, resample_freq = ("3H", "9H")
     start = "1969-12-31T12:07:01"
-    index_kwargs = dict(start=start, periods=12, freq=initial_freq)
+    index_kwargs: DateRangeKwargs = dict(start=start, periods=12, freq=initial_freq)
     datetime_index = pd.date_range(**index_kwargs)
     cftime_index = xr.cftime_range(**index_kwargs)
     da_datetimeindex = da(datetime_index)