Escalate .apply deprecation to FutureWarning (GH11721)

doc/whats-new.rst

@@ -143,6 +143,14 @@ Deprecations
   :py:attr:`DataTree.lineage` warns once instead of twice (:issue:`11721`,
   :pull:`11724`).
   By `Daisy DAI <https://github.com/ShinoKana>`_.
+- :py:meth:`Dataset.apply`,
+  :py:meth:`core.groupby.DataArrayGroupBy.apply`,
+  :py:meth:`core.groupby.DatasetGroupBy.apply`,
+  :py:meth:`core.resample.DataArrayResample.apply` and
+  :py:meth:`core.resample.DatasetResample.apply` now emit a ``FutureWarning``
+  instead of ``PendingDeprecationWarning``. Use ``.map`` instead (:issue:`11721`,
+  :pull:`11784`).
+  By `Anjali Kashide <https://github.com/Anju522>`_.
 
 
 Bug Fixes

xarray/core/dataset.py

@@ -7155,10 +7155,9 @@ def apply(
         --------
         Dataset.map
         """
-        warnings.warn(
-            "Dataset.apply may be deprecated in the future. Using Dataset.map is encouraged",
-            PendingDeprecationWarning,
-            stacklevel=2,
+        emit_user_level_warning(
+            "Dataset.apply is deprecated, use Dataset.map instead.",
+            FutureWarning,
         )
         return self.map(func, keep_attrs, args, **kwargs)
 

xarray/core/groupby.py

@@ -1738,10 +1738,9 @@ def apply(self, func, shortcut=False, args=(), **kwargs):
         --------
         DataArrayGroupBy.map
         """
-        warnings.warn(
-            "GroupBy.apply may be deprecated in the future. Using GroupBy.map is encouraged",
-            PendingDeprecationWarning,
-            stacklevel=2,
+        emit_user_level_warning(
+            "GroupBy.apply is deprecated, use GroupBy.map instead.",
+            FutureWarning,
         )
         return self.map(func, shortcut=shortcut, args=args, **kwargs)
 
@@ -1918,10 +1917,9 @@ def apply(self, func, args=(), shortcut=None, **kwargs):
         --------
         DatasetGroupBy.map
         """
-        warnings.warn(
-            "GroupBy.apply may be deprecated in the future. Using GroupBy.map is encouraged",
-            PendingDeprecationWarning,
-            stacklevel=2,
+        emit_user_level_warning(
+            "GroupBy.apply is deprecated, use GroupBy.map instead.",
+            FutureWarning,
         )
         return self.map(func, shortcut=shortcut, args=args, **kwargs)
 

xarray/core/resample.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-import warnings
 from collections.abc import Callable, Hashable, Iterable, Sequence
 from typing import TYPE_CHECKING, Any, Literal, override
 
@@ -10,6 +9,7 @@
 )
 from xarray.core.groupby import DataArrayGroupByBase, DatasetGroupByBase, GroupBy
 from xarray.core.types import Dims, InterpOptions, T_Xarray
+from xarray.core.utils import emit_user_level_warning
 
 if TYPE_CHECKING:
     from xarray.core.dataarray import DataArray
@@ -382,10 +382,9 @@ def apply(self, func, args=(), shortcut=None, **kwargs):
         --------
         DataArrayResample.map
         """
-        warnings.warn(
-            "Resample.apply may be deprecated in the future. Using Resample.map is encouraged",
-            PendingDeprecationWarning,
-            stacklevel=2,
+        emit_user_level_warning(
+            "Resample.apply is deprecated, use Resample.map instead.",
+            FutureWarning,
         )
         return self.map(func=func, shortcut=shortcut, args=args, **kwargs)
 
@@ -469,10 +468,9 @@ def apply(self, func, args=(), shortcut=None, **kwargs):
         --------
         DataSetResample.map
         """
-        warnings.warn(
-            "Resample.apply may be deprecated in the future. Using Resample.map is encouraged",
-            PendingDeprecationWarning,
-            stacklevel=2,
+        emit_user_level_warning(
+            "Resample.apply is deprecated, use Resample.map instead.",
+            FutureWarning,
         )
         return self.map(func=func, shortcut=shortcut, args=args, **kwargs)
 

xarray/tests/test_dataset.py

@@ -6844,11 +6844,11 @@ def modify_attr(da):
         result = ds.map(modify_attr, keep_attrs=False)
         assert result["test"].attrs == {"original": "modified", "extra": "added"}
 
-    def test_apply_pending_deprecated_map(self) -> None:
+    def test_apply_deprecated_map(self) -> None:
         data = create_test_data()
         data.attrs["foo"] = "bar"
 
-        with pytest.warns(PendingDeprecationWarning):
+        with pytest.warns(FutureWarning, match=r"Dataset\.apply is deprecated"):
             # data.apply keeps all attrs by default
             assert_identical(data.apply(np.mean), data.mean())
 

xarray/tests/test_groupby.py

@@ -274,6 +274,33 @@ def func(arg1, arg2, arg3=0):
     assert_identical(expected, actual)
 
 
+@pytest.mark.parametrize("use_da", [True, False])
+def test_groupby_apply_deprecated(use_da: bool) -> None:
+    obj: xr.DataArray | xr.Dataset = xr.DataArray(
+        [1.0, 2.0, 3.0, 4.0], [("x", [1, 1, 2, 2])]
+    )
+    if not use_da:
+        obj = obj.to_dataset(name="foo")
+
+    expected = obj.groupby("x").map(lambda g: g - g.mean())
+    with pytest.warns(FutureWarning, match=r"GroupBy\.apply is deprecated"):
+        actual = obj.groupby("x").apply(lambda g: g - g.mean())
+    assert_identical(expected, actual)
+
+
+@pytest.mark.parametrize("use_da", [True, False])
+def test_resample_apply_deprecated(use_da: bool) -> None:
+    times = pd.date_range("2000-01-01", freq="6h", periods=8)
+    obj: xr.DataArray | xr.Dataset = xr.DataArray(np.arange(8.0), [("time", times)])
+    if not use_da:
+        obj = obj.to_dataset(name="foo")
+
+    expected = obj.resample(time="1D").map(lambda g: g.mean("time"))
+    with pytest.warns(FutureWarning, match=r"Resample\.apply is deprecated"):
+        actual = obj.resample(time="1D").apply(lambda g: g.mean("time"))
+    assert_identical(expected, actual)
+
+
 def test_da_groupby_empty() -> None:
     empty_array = xr.DataArray([], dims="dim")