Add T_DuckArray type hint to Variable.data (#8203)

* Add T_DuckArray

* Add type to variable.data

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fixes

* Update variable.py

* Update variable.py

* Update variable.py

* Update variable.py

* Update variable.py

* chunk renaming

* Update parallelcompat.py

* fix attrs?

* Update alignment.py

* Update test_parallelcompat.py

* Update test_variable.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update test_variable.py

* Update test_variable.py

* Update test_variable.py

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Anderson Banihirwe <13301940+andersy005@users.noreply.github.com>

xarray/core/alignment.py

@@ -26,7 +26,7 @@
 if TYPE_CHECKING:
     from xarray.core.dataarray import DataArray
     from xarray.core.dataset import Dataset
-    from xarray.core.types import JoinOptions, T_DataArray, T_Dataset
+    from xarray.core.types import JoinOptions, T_DataArray, T_Dataset, T_DuckArray
 
 
 def reindex_variables(
@@ -173,7 +173,7 @@ def __init__(
 
     def _normalize_indexes(
         self,
-        indexes: Mapping[Any, Any],
+        indexes: Mapping[Any, Any | T_DuckArray],
     ) -> tuple[NormalizedIndexes, NormalizedIndexVars]:
         """Normalize the indexes/indexers used for re-indexing or alignment.
 
@@ -194,7 +194,7 @@ def _normalize_indexes(
                         f"Indexer has dimensions {idx.dims} that are different "
                         f"from that to be indexed along '{k}'"
                     )
-                data = as_compatible_data(idx)
+                data: T_DuckArray = as_compatible_data(idx)
                 pd_idx = safe_cast_to_index(data)
                 pd_idx.name = k
                 if isinstance(pd_idx, pd.MultiIndex):

xarray/core/dataset.py

@@ -7481,7 +7481,7 @@ def _unary_op(self: T_Dataset, f, *args, **kwargs) -> T_Dataset:
             else:
                 variables[k] = f(v, *args, **kwargs)
                 if keep_attrs:
-                    variables[k].attrs = v._attrs
+                    variables[k]._attrs = v._attrs
         attrs = self._attrs if keep_attrs else None
         return self._replace_with_new_dims(variables, attrs=attrs)
 

xarray/core/parallelcompat.py

@@ -25,7 +25,7 @@
 T_ChunkedArray = TypeVar("T_ChunkedArray")
 
 if TYPE_CHECKING:
-    from xarray.core.types import T_Chunks, T_NormalizedChunks
+    from xarray.core.types import T_Chunks, T_DuckArray, T_NormalizedChunks
 
 
 @functools.lru_cache(maxsize=1)
@@ -257,7 +257,7 @@ def normalize_chunks(
 
     @abstractmethod
     def from_array(
-        self, data: np.ndarray, chunks: T_Chunks, **kwargs
+        self, data: T_DuckArray | np.typing.ArrayLike, chunks: T_Chunks, **kwargs
     ) -> T_ChunkedArray:
         """
         Create a chunked array from a non-chunked numpy-like array.

xarray/core/types.py

@@ -161,6 +161,10 @@ def copy(
 T_DataWithCoords = TypeVar("T_DataWithCoords", bound="DataWithCoords")
 T_Alignable = TypeVar("T_Alignable", bound="Alignable")
 
+# Temporary placeholder for indicating an array api compliant type.
+# hopefully in the future we can narrow this down more:
+T_DuckArray = TypeVar("T_DuckArray", bound=Any)
+
 ScalarOrArray = Union["ArrayLike", np.generic, np.ndarray, "DaskArray"]
 DsCompatible = Union["Dataset", "DataArray", "Variable", "GroupBy", "ScalarOrArray"]
 DaCompatible = Union["DataArray", "Variable", "DataArrayGroupBy", "ScalarOrArray"]

xarray/core/utils.py

@@ -73,7 +73,7 @@
 import pandas as pd
 
 if TYPE_CHECKING:
-    from xarray.core.types import Dims, ErrorOptionsWithWarn, OrderedDims
+    from xarray.core.types import Dims, ErrorOptionsWithWarn, OrderedDims, T_DuckArray
 
 K = TypeVar("K")
 V = TypeVar("V")
@@ -253,7 +253,7 @@ def is_list_like(value: Any) -> TypeGuard[list | tuple]:
     return isinstance(value, (list, tuple))
 
 
-def is_duck_array(value: Any) -> bool:
+def is_duck_array(value: Any) -> TypeGuard[T_DuckArray]:
     if isinstance(value, np.ndarray):
         return True
     return (

xarray/core/variable.py

@@ -8,7 +8,7 @@
 from collections.abc import Hashable, Iterable, Mapping, Sequence
 from datetime import timedelta
 from functools import partial
-from typing import TYPE_CHECKING, Any, Callable, Literal, NoReturn
+from typing import TYPE_CHECKING, Any, Callable, Literal, NoReturn, cast
 
 import numpy as np
 import pandas as pd
@@ -66,6 +66,7 @@
         PadModeOptions,
         PadReflectOptions,
         QuantileMethods,
+        T_DuckArray,
         T_Variable,
     )
 
@@ -86,7 +87,7 @@ class MissingDimensionsError(ValueError):
     # TODO: move this to an xarray.exceptions module?
 
 
-def as_variable(obj, name=None) -> Variable | IndexVariable:
+def as_variable(obj: T_DuckArray | Any, name=None) -> Variable | IndexVariable:
     """Convert an object into a Variable.
 
     Parameters
@@ -142,7 +143,7 @@ def as_variable(obj, name=None) -> Variable | IndexVariable:
     elif isinstance(obj, (set, dict)):
         raise TypeError(f"variable {name!r} has invalid type {type(obj)!r}")
     elif name is not None:
-        data = as_compatible_data(obj)
+        data: T_DuckArray = as_compatible_data(obj)
         if data.ndim != 1:
             raise MissingDimensionsError(
                 f"cannot set variable {name!r} with {data.ndim!r}-dimensional data "
@@ -230,7 +231,9 @@ def _possibly_convert_datetime_or_timedelta_index(data):
         return data
 
 
-def as_compatible_data(data, fastpath: bool = False):
+def as_compatible_data(
+    data: T_DuckArray | ArrayLike, fastpath: bool = False
+) -> T_DuckArray:
     """Prepare and wrap data to put in a Variable.
 
     - If data does not have the necessary attributes, convert it to ndarray.
@@ -243,7 +246,7 @@ def as_compatible_data(data, fastpath: bool = False):
     """
     if fastpath and getattr(data, "ndim", 0) > 0:
         # can't use fastpath (yet) for scalars
-        return _maybe_wrap_data(data)
+        return cast("T_DuckArray", _maybe_wrap_data(data))
 
     from xarray.core.dataarray import DataArray
 
@@ -252,7 +255,7 @@ def as_compatible_data(data, fastpath: bool = False):
 
     if isinstance(data, NON_NUMPY_SUPPORTED_ARRAY_TYPES):
         data = _possibly_convert_datetime_or_timedelta_index(data)
-        return _maybe_wrap_data(data)
+        return cast("T_DuckArray", _maybe_wrap_data(data))
 
     if isinstance(data, tuple):
         data = utils.to_0d_object_array(data)
@@ -279,7 +282,7 @@ def as_compatible_data(data, fastpath: bool = False):
     if not isinstance(data, np.ndarray) and (
         hasattr(data, "__array_function__") or hasattr(data, "__array_namespace__")
     ):
-        return data
+        return cast("T_DuckArray", data)
 
     # validate whether the data is valid data types.
     data = np.asarray(data)
@@ -335,7 +338,14 @@ class Variable(AbstractArray, NdimSizeLenMixin, VariableArithmetic):
 
     __slots__ = ("_dims", "_data", "_attrs", "_encoding")
 
-    def __init__(self, dims, data, attrs=None, encoding=None, fastpath=False):
+    def __init__(
+        self,
+        dims,
+        data: T_DuckArray | ArrayLike,
+        attrs=None,
+        encoding=None,
+        fastpath=False,
+    ):
         """
         Parameters
         ----------
@@ -355,9 +365,9 @@ def __init__(self, dims, data, attrs=None, encoding=None, fastpath=False):
             Well-behaved code to serialize a Variable should ignore
             unrecognized encoding items.
         """
-        self._data = as_compatible_data(data, fastpath=fastpath)
+        self._data: T_DuckArray = as_compatible_data(data, fastpath=fastpath)
         self._dims = self._parse_dimensions(dims)
-        self._attrs = None
+        self._attrs: dict[Any, Any] | None = None
         self._encoding = None
         if attrs is not None:
             self.attrs = attrs
@@ -410,7 +420,7 @@ def _in_memory(self):
         )
 
     @property
-    def data(self) -> Any:
+    def data(self: T_Variable):
         """
         The Variable's data as an array. The underlying array type
         (e.g. dask, sparse, pint) is preserved.
@@ -429,12 +439,12 @@ def data(self) -> Any:
             return self.values
 
     @data.setter
-    def data(self, data):
+    def data(self: T_Variable, data: T_DuckArray | ArrayLike) -> None:
         data = as_compatible_data(data)
-        if data.shape != self.shape:
+        if data.shape != self.shape:  # type: ignore[attr-defined]
             raise ValueError(
                 f"replacement data must match the Variable's shape. "
-                f"replacement data has shape {data.shape}; Variable has shape {self.shape}"
+                f"replacement data has shape {data.shape}; Variable has shape {self.shape}"  # type: ignore[attr-defined]
             )
         self._data = data
 
@@ -996,7 +1006,7 @@ def reset_encoding(self: T_Variable) -> T_Variable:
         return self._replace(encoding={})
 
     def copy(
-        self: T_Variable, deep: bool = True, data: ArrayLike | None = None
+        self: T_Variable, deep: bool = True, data: T_DuckArray | ArrayLike | None = None
     ) -> T_Variable:
         """Returns a copy of this object.
 
@@ -1058,24 +1068,26 @@ def copy(
     def _copy(
         self: T_Variable,
         deep: bool = True,
-        data: ArrayLike | None = None,
+        data: T_DuckArray | ArrayLike | None = None,
         memo: dict[int, Any] | None = None,
     ) -> T_Variable:
         if data is None:
-            ndata = self._data
+            data_old = self._data
 
-            if isinstance(ndata, indexing.MemoryCachedArray):
+            if isinstance(data_old, indexing.MemoryCachedArray):
                 # don't share caching between copies
-                ndata = indexing.MemoryCachedArray(ndata.array)
+                ndata = indexing.MemoryCachedArray(data_old.array)
+            else:
+                ndata = data_old
 
             if deep:
                 ndata = copy.deepcopy(ndata, memo)
 
         else:
             ndata = as_compatible_data(data)
-            if self.shape != ndata.shape:
+            if self.shape != ndata.shape:  # type: ignore[attr-defined]
                 raise ValueError(
-                    f"Data shape {ndata.shape} must match shape of object {self.shape}"
+                    f"Data shape {ndata.shape} must match shape of object {self.shape}"  # type: ignore[attr-defined]
                 )
 
         attrs = copy.deepcopy(self._attrs, memo) if deep else copy.copy(self._attrs)
@@ -1248,11 +1260,11 @@ def chunk(
             inline_array=inline_array,
         )
 
-        data = self._data
-        if chunkmanager.is_chunked_array(data):
-            data = chunkmanager.rechunk(data, chunks)  # type: ignore[arg-type]
+        data_old = self._data
+        if chunkmanager.is_chunked_array(data_old):
+            data_chunked = chunkmanager.rechunk(data_old, chunks)  # type: ignore[arg-type]
         else:
-            if isinstance(data, indexing.ExplicitlyIndexed):
+            if isinstance(data_old, indexing.ExplicitlyIndexed):
                 # Unambiguously handle array storage backends (like NetCDF4 and h5py)
                 # that can't handle general array indexing. For example, in netCDF4 you
                 # can do "outer" indexing along two dimensions independent, which works
@@ -1261,20 +1273,22 @@ def chunk(
                 # Using OuterIndexer is a pragmatic choice: dask does not yet handle
                 # different indexing types in an explicit way:
                 # https://github.com/dask/dask/issues/2883
-                data = indexing.ImplicitToExplicitIndexingAdapter(
-                    data, indexing.OuterIndexer
+                ndata = indexing.ImplicitToExplicitIndexingAdapter(
+                    data_old, indexing.OuterIndexer
                 )
+            else:
+                ndata = data_old
 
             if utils.is_dict_like(chunks):
-                chunks = tuple(chunks.get(n, s) for n, s in enumerate(data.shape))
+                chunks = tuple(chunks.get(n, s) for n, s in enumerate(ndata.shape))
 
-            data = chunkmanager.from_array(
-                data,
+            data_chunked = chunkmanager.from_array(
+                ndata,
                 chunks,  # type: ignore[arg-type]
                 **_from_array_kwargs,
             )
 
-        return self._replace(data=data)
+        return self._replace(data=data_chunked)
 
     def to_numpy(self) -> np.ndarray:
         """Coerces wrapped data to numpy and returns a numpy.ndarray"""

xarray/tests/test_parallelcompat.py

@@ -12,7 +12,7 @@
     guess_chunkmanager,
     list_chunkmanagers,
 )
-from xarray.core.types import T_Chunks, T_NormalizedChunks
+from xarray.core.types import T_Chunks, T_DuckArray, T_NormalizedChunks
 from xarray.tests import has_dask, requires_dask
 
 
@@ -76,7 +76,7 @@ def normalize_chunks(
         return normalize_chunks(chunks, shape, limit, dtype, previous_chunks)
 
     def from_array(
-        self, data: np.ndarray, chunks: T_Chunks, **kwargs
+        self, data: T_DuckArray | np.typing.ArrayLike, chunks: T_Chunks, **kwargs
     ) -> DummyChunkedArray:
         from dask import array as da
 

xarray/tests/test_variable.py

@@ -5,6 +5,7 @@
 from copy import copy, deepcopy
 from datetime import datetime, timedelta
 from textwrap import dedent
+from typing import Generic
 
 import numpy as np
 import pandas as pd
@@ -26,6 +27,7 @@
     VectorizedIndexer,
 )
 from xarray.core.pycompat import array_type
+from xarray.core.types import T_DuckArray
 from xarray.core.utils import NDArrayMixin
 from xarray.core.variable import as_compatible_data, as_variable
 from xarray.tests import (
@@ -2529,7 +2531,7 @@ def test_to_index_variable_copy(self) -> None:
         assert a.dims == ("x",)
 
 
-class TestAsCompatibleData:
+class TestAsCompatibleData(Generic[T_DuckArray]):
     def test_unchanged_types(self):
         types = (np.asarray, PandasIndexingAdapter, LazilyIndexedArray)
         for t in types:
@@ -2610,17 +2612,17 @@ def test_tz_datetime(self) -> None:
         times_s = times_ns.astype(pd.DatetimeTZDtype("s", tz))
         with warnings.catch_warnings():
             warnings.simplefilter("ignore")
-            actual = as_compatible_data(times_s)
+            actual: T_DuckArray = as_compatible_data(times_s)
         assert actual.array == times_s
         assert actual.array.dtype == pd.DatetimeTZDtype("ns", tz)
 
         series = pd.Series(times_s)
         with warnings.catch_warnings():
             warnings.simplefilter("ignore")
-            actual = as_compatible_data(series)
+            actual2: T_DuckArray = as_compatible_data(series)
 
-        np.testing.assert_array_equal(actual, series.values)
-        assert actual.dtype == np.dtype("datetime64[ns]")
+        np.testing.assert_array_equal(actual2, series.values)
+        assert actual2.dtype == np.dtype("datetime64[ns]")
 
     def test_full_like(self) -> None:
         # For more thorough tests, see test_variable.py