fix: Filter out StringDType even when the backing array is not NumpyExtensionArray

pyproject.toml

@@ -33,6 +33,7 @@ accel = [
   "numba>=0.59",
   "flox>=0.9",
   "opt_einsum",
+  "numpy<2.3",    # numba has not updated yet: https://github.com/numba/numba/issues/10105
 ]
 complete = ["xarray[accel,etc,io,parallel,viz]"]
 io = [
@@ -324,6 +325,8 @@ known-first-party = ["xarray"]
 [tool.ruff.lint.flake8-tidy-imports]
 # Disallow all relative imports.
 ban-relative-imports = "all"
+[tool.ruff.lint.flake8-tidy-imports.banned-api]
+"pandas.api.types.is_extension_array_dtype".msg = "Use xarray.core.utils.is_allowed_extension_array{_dtype} instead.  Only use the banend API if the incoming data has already been sanitized by xarray"
 
 [tool.pytest.ini_options]
 addopts = [

xarray/computation/ops.py

@@ -8,12 +8,15 @@
 from __future__ import annotations
 
 import operator
-from typing import Literal
+from typing import TYPE_CHECKING, Literal
 
 import numpy as np
 
 from xarray.core import dtypes, duck_array_ops
 
+if TYPE_CHECKING:
+    pass
+
 try:
     import bottleneck as bn
 
@@ -158,8 +161,8 @@ def fillna(data, other, join="left", dataset_join="left"):
     )
 
 
-# Unsure why we get a mypy error here
-def where_method(self, cond, other=dtypes.NA):  # type: ignore[has-type]
+# TODO: type this properly
+def where_method(self, cond, other=dtypes.NA):  # type: ignore[unused-ignore,has-type]
     """Return elements from `self` or `other` depending on `cond`.
 
     Parameters

xarray/core/dataset.py

@@ -26,7 +26,6 @@
 
 import numpy as np
 import pandas as pd
-from pandas.api.types import is_extension_array_dtype
 
 from xarray.coding.calendar_ops import convert_calendar, interp_calendar
 from xarray.coding.cftimeindex import CFTimeIndex, _parse_array_of_cftime_strings
@@ -91,6 +90,7 @@
     either_dict_or_kwargs,
     emit_user_level_warning,
     infix_dims,
+    is_allowed_extension_array,
     is_dict_like,
     is_duck_array,
     is_duck_dask_array,
@@ -6780,7 +6780,7 @@ def reduce(
             elif (
                 # Some reduction functions (e.g. std, var) need to run on variables
                 # that don't have the reduce dims: PR5393
-                not is_extension_array_dtype(var.dtype)
+                not pd.api.types.is_extension_array_dtype(var.dtype)  # noqa: TID251
                 and (
                     not reduce_dims
                     or not numeric_only
@@ -7105,12 +7105,12 @@ def _to_dataframe(self, ordered_dims: Mapping[Any, int]):
         non_extension_array_columns = [
             k
             for k in columns_in_order
-            if not is_extension_array_dtype(self.variables[k].data)
+            if not pd.api.types.is_extension_array_dtype(self.variables[k].data)  # noqa: TID251
         ]
         extension_array_columns = [
             k
             for k in columns_in_order
-            if is_extension_array_dtype(self.variables[k].data)
+            if pd.api.types.is_extension_array_dtype(self.variables[k].data)  # noqa: TID251
         ]
         extension_array_columns_different_index = [
             k
@@ -7302,7 +7302,7 @@ def from_dataframe(cls, dataframe: pd.DataFrame, sparse: bool = False) -> Self:
         arrays = []
         extension_arrays = []
         for k, v in dataframe.items():
-            if not is_extension_array_dtype(v) or isinstance(
+            if not is_allowed_extension_array(v) or isinstance(
                 v.array, UNSUPPORTED_EXTENSION_ARRAY_TYPES
             ):
                 arrays.append((k, np.asarray(v)))

xarray/core/dtypes.py

@@ -4,7 +4,7 @@
 from typing import Any
 
 import numpy as np
-from pandas.api.types import is_extension_array_dtype
+import pandas as pd
 
 from xarray.compat import array_api_compat, npcompat
 from xarray.compat.npcompat import HAS_STRING_DTYPE
@@ -213,7 +213,7 @@ def isdtype(dtype, kind: str | tuple[str, ...], xp=None) -> bool:
 
     if isinstance(dtype, np.dtype):
         return npcompat.isdtype(dtype, kind)
-    elif is_extension_array_dtype(dtype):
+    elif pd.api.types.is_extension_array_dtype(dtype):  # noqa: TID251
         # we never want to match pandas extension array dtypes
         return False
     else:

xarray/core/duck_array_ops.py

@@ -23,7 +23,6 @@
     take,
     unravel_index,  # noqa: F401
 )
-from pandas.api.types import is_extension_array_dtype
 
 from xarray.compat import dask_array_compat, dask_array_ops
 from xarray.compat.array_api_compat import get_array_namespace
@@ -184,7 +183,7 @@ def isnull(data):
         dtype = xp.bool_ if hasattr(xp, "bool_") else xp.bool
         return full_like(data, dtype=dtype, fill_value=False)
     # at this point, array should have dtype=object
-    elif isinstance(data, np.ndarray) or is_extension_array_dtype(data):
+    elif isinstance(data, np.ndarray) or pd.api.types.is_extension_array_dtype(data):  # noqa: TID251
         return pandas_isnull(data)
     else:
         # Not reachable yet, but intended for use with other duck array
@@ -266,10 +265,12 @@ def asarray(data, xp=np, dtype=None):
 
 def as_shared_dtype(scalars_or_arrays, xp=None):
     """Cast arrays to a shared dtype using xarray's type promotion rules."""
-    if any(is_extension_array_dtype(x) for x in scalars_or_arrays):
-        extension_array_types = [
-            x.dtype for x in scalars_or_arrays if is_extension_array_dtype(x)
-        ]
+    extension_array_types = [
+        x.dtype
+        for x in scalars_or_arrays
+        if pd.api.types.is_extension_array_dtype(x)  # noqa: TID251
+    ]
+    if len(extension_array_types) >= 1:
         non_nans = [x for x in scalars_or_arrays if not isna(x)]
         if len(extension_array_types) == len(non_nans) and all(
             isinstance(x, type(extension_array_types[0])) for x in extension_array_types

xarray/core/extension_array.py

@@ -8,10 +8,9 @@
 import numpy as np
 import pandas as pd
 from packaging.version import Version
-from pandas.api.types import is_extension_array_dtype
 
 from xarray.core.types import DTypeLikeSave, T_ExtensionArray
-from xarray.core.utils import NDArrayMixin
+from xarray.core.utils import NDArrayMixin, is_allowed_extension_array
 
 HANDLED_EXTENSION_ARRAY_FUNCTIONS: dict[Callable, Callable] = {}
 
@@ -100,10 +99,11 @@ def __post_init__(self):
             raise TypeError(f"{self.array} is not an pandas ExtensionArray.")
         # This does not use the UNSUPPORTED_EXTENSION_ARRAY_TYPES whitelist because
         # we do support extension arrays from datetime, for example, that need
-        # duck array support internally via this class.
-        if isinstance(self.array, pd.arrays.NumpyExtensionArray):
+        # duck array support internally via this class.  These can appear from `DatetimeIndex`
+        # wrapped by `PandasIndex` internally, for example.
+        if not is_allowed_extension_array(self.array):
             raise TypeError(
-                "`NumpyExtensionArray` should be converted to a numpy array in `xarray` internally."
+                f"{self.array.dtype!r} should be converted to a numpy array in `xarray` internally."
             )
 
     def __array_function__(self, func, types, args, kwargs):
@@ -126,7 +126,7 @@ def replace_duck_with_extension_array(args) -> list:
         if func not in HANDLED_EXTENSION_ARRAY_FUNCTIONS:
             raise KeyError("Function not registered for pandas extension arrays.")
         res = HANDLED_EXTENSION_ARRAY_FUNCTIONS[func](*args, **kwargs)
-        if is_extension_array_dtype(res):
+        if is_allowed_extension_array(res):
             return PandasExtensionArray(res)
         return res
 
@@ -135,7 +135,7 @@ def __array_ufunc__(self, ufunc, method, *inputs, **kwargs):
 
     def __getitem__(self, key) -> PandasExtensionArray[T_ExtensionArray]:
         item = self.array[key]
-        if is_extension_array_dtype(item):
+        if is_allowed_extension_array(item):
             return PandasExtensionArray(item)
         if np.isscalar(item) or isinstance(key, int):
             return PandasExtensionArray(type(self.array)._from_sequence([item]))  # type: ignore[call-arg,attr-defined,unused-ignore]

xarray/core/indexes.py

@@ -23,6 +23,7 @@
     Frozen,
     emit_user_level_warning,
     get_valid_numpy_dtype,
+    is_allowed_extension_array_dtype,
     is_dict_like,
     is_scalar,
 )
@@ -666,9 +667,8 @@ def __init__(
 
         self.index = index
         self.dim = dim
-
         if coord_dtype is None:
-            if pd.api.types.is_extension_array_dtype(index.dtype):
+            if is_allowed_extension_array_dtype(index.dtype):
                 cast(pd.api.extensions.ExtensionDtype, index.dtype)
                 coord_dtype = index.dtype
             else:

xarray/core/indexing.py

@@ -24,6 +24,8 @@
     NDArrayMixin,
     either_dict_or_kwargs,
     get_valid_numpy_dtype,
+    is_allowed_extension_array,
+    is_allowed_extension_array_dtype,
     is_duck_array,
     is_duck_dask_array,
     is_scalar,
@@ -1763,12 +1765,12 @@ def __init__(
         self.array = safe_cast_to_index(array)
 
         if dtype is None:
-            if pd.api.types.is_extension_array_dtype(array.dtype):
+            if is_allowed_extension_array(array):
                 cast(pd.api.extensions.ExtensionDtype, array.dtype)
                 self._dtype = array.dtype
             else:
                 self._dtype = get_valid_numpy_dtype(array)
-        elif pd.api.types.is_extension_array_dtype(dtype):
+        elif is_allowed_extension_array_dtype(dtype):
             self._dtype = cast(pd.api.extensions.ExtensionDtype, dtype)
         else:
             self._dtype = np.dtype(cast(DTypeLike, dtype))
@@ -1816,10 +1818,7 @@ def get_duck_array(self) -> np.ndarray | PandasExtensionArray:
         # We return an PandasExtensionArray wrapper type that satisfies
         # duck array protocols.
         # `NumpyExtensionArray` is excluded
-        if pd.api.types.is_extension_array_dtype(self.array) and not isinstance(
-            self.array.array,
-            pd.arrays.NumpyExtensionArray,  # type: ignore[attr-defined]
-        ):
+        if is_allowed_extension_array(self.array):
             from xarray.core.extension_array import PandasExtensionArray
 
             return PandasExtensionArray(self.array.array)
@@ -1916,7 +1915,7 @@ def copy(self, deep: bool = True) -> Self:
 
     @property
     def nbytes(self) -> int:
-        if pd.api.types.is_extension_array_dtype(self.dtype):
+        if is_allowed_extension_array(self.array):
             return self.array.nbytes
 
         dtype = self._get_numpy_dtype()

xarray/core/utils.py

@@ -104,6 +104,20 @@
 T = TypeVar("T")
 
 
+def is_allowed_extension_array_dtype(dtype: Any):
+    return pd.api.types.is_extension_array_dtype(dtype) and not isinstance(  # noqa: TID251
+        dtype, pd.StringDtype
+    )
+
+
+def is_allowed_extension_array(array: Any) -> bool:
+    return (
+        hasattr(array, "dtype")
+        and is_allowed_extension_array_dtype(array.dtype)
+        and not isinstance(array, pd.arrays.NumpyExtensionArray)  # type: ignore[attr-defined]
+    )
+
+
 def alias_message(old_name: str, new_name: str) -> str:
     return f"{old_name} has been deprecated. Use {new_name} instead."
 

xarray/core/variable.py

@@ -40,6 +40,7 @@
     emit_user_level_warning,
     ensure_us_time_resolution,
     infix_dims,
+    is_allowed_extension_array,
     is_dict_like,
     is_duck_array,
     is_duck_dask_array,
@@ -198,7 +199,9 @@ def _maybe_wrap_data(data):
         return PandasIndexingAdapter(data)
     if isinstance(data, UNSUPPORTED_EXTENSION_ARRAY_TYPES):
         return data.to_numpy()
-    if isinstance(data, pd.api.extensions.ExtensionArray):
+    if isinstance(
+        data, pd.api.extensions.ExtensionArray
+    ) and is_allowed_extension_array(data):
         return PandasExtensionArray(data)
     return data
 
@@ -261,7 +264,8 @@ def convert_non_numpy_type(data):
     if isinstance(data, pd.Series | pd.DataFrame):
         if (
             isinstance(data, pd.Series)
-            and pd.api.types.is_extension_array_dtype(data)
+            and is_allowed_extension_array(data.array)
+            # Some datetime types are not allowed as well as backing Variable types
             and not isinstance(data.array, UNSUPPORTED_EXTENSION_ARRAY_TYPES)
         ):
             pandas_data = data.array

xarray/tests/test_pandas_to_xarray.py

@@ -37,6 +37,7 @@
 import pandas as pd
 import pandas._testing as tm
 import pytest
+from packaging.version import Version
 from pandas import (
     Categorical,
     CategoricalIndex,
@@ -171,7 +172,9 @@ def test_to_xarray_with_multiindex(self, df):
 
         result = result.to_dataframe()
         expected = df.copy()
-        expected["f"] = expected["f"].astype(object)
+        expected["f"] = expected["f"].astype(
+            object if Version(pd.__version__) < Version("3.0.0dev0") else str
+        )
         expected.columns.name = None
         tm.assert_frame_equal(result, expected)
 

xarray/tests/test_variable.py

@@ -1594,7 +1594,7 @@ def test_pandas_categorical_dtype(self):
         data = pd.Categorical(np.arange(10, dtype="int64"))
         v = self.cls("x", data)
         print(v)  # should not error
-        assert pd.api.types.is_extension_array_dtype(v.dtype)
+        assert isinstance(v.dtype, pd.CategoricalDtype)
 
     def test_squeeze(self):
         v = Variable(["x", "y"], [[1]])