Dims can be a single Hashable

xarray/core/types.py

@@ -2,7 +2,7 @@
 
 import datetime
 import sys
-from collections.abc import Hashable, Iterable, Iterator, Mapping, Sequence
+from collections.abc import Hashable, Iterator, Mapping, Sequence
 from typing import (
     TYPE_CHECKING,
     Any,
@@ -182,8 +182,7 @@ def copy(
 DsCompatible = Union["Dataset", "DaCompatible"]
 GroupByCompatible = Union["Dataset", "DataArray"]
 
-Dims = Union[str, Iterable[Hashable], "ellipsis", None]
-OrderedDims = Union[str, Sequence[Union[Hashable, "ellipsis"]], "ellipsis", None]
+Dims = Union[Hashable, "ellipsis", Sequence[Union[Hashable, "ellipsis"]], None]
 
 # FYI in some cases we don't allow `None`, which this doesn't take account of.
 T_ChunkDim: TypeAlias = Union[int, Literal["auto"], None, tuple[int, ...]]

xarray/core/utils.py

@@ -76,7 +76,7 @@
 import pandas as pd
 
 if TYPE_CHECKING:
-    from xarray.core.types import Dims, ErrorOptionsWithWarn, OrderedDims, T_DuckArray
+    from xarray.core.types import Dims, ErrorOptionsWithWarn, T_DuckArray
 
 K = TypeVar("K")
 V = TypeVar("V")
@@ -1051,7 +1051,7 @@ def parse_dims(
 
 @overload
 def parse_ordered_dims(
-    dim: str | Sequence[Hashable | ellipsis] | T_None,
+    dim: Dims,
     all_dims: tuple[Hashable, ...],
     *,
     check_exists: bool = True,
@@ -1062,7 +1062,7 @@ def parse_ordered_dims(
 
 @overload
 def parse_ordered_dims(
-    dim: str | Sequence[Hashable | ellipsis] | T_None,
+    dim: Dims,
     all_dims: tuple[Hashable, ...],
     *,
     check_exists: bool = True,
@@ -1072,24 +1072,22 @@ def parse_ordered_dims(
 
 
 def parse_ordered_dims(
-    dim: OrderedDims,
+    dim: Dims,
     all_dims: tuple[Hashable, ...],
     *,
     check_exists: bool = True,
     replace_none: bool = True,
 ) -> tuple[Hashable, ...] | None | ellipsis:
     """Parse one or more dimensions.
 
-    A single dimension must be always a str, multiple dimensions
-    can be Hashables. This supports e.g. using a tuple as a dimension.
     An ellipsis ("...") in a sequence of dimensions will be
     replaced with all remaining dimensions. This only makes sense when
     the input is a sequence and not e.g. a set.
 
     Parameters
     ----------
-    dim : str, Sequence of Hashable or "...", "..." or None
-        Dimension(s) to parse. If "..." appears in a Sequence
+    dim : Hashable or ... (or Sequence thereof), or None
+        Dimension(s) to parse. If ... appears in a Sequence
         it always gets replaced with all remaining dims
     all_dims : tuple of Hashable
         All possible dimensions.
@@ -1103,7 +1101,7 @@ def parse_ordered_dims(
     parsed_dims : tuple of Hashable
         Input dimensions as a tuple.
     """
-    if dim is not None and dim is not ... and not isinstance(dim, str) and ... in dim:
+    if isinstance(dim, Sequence) and not isinstance(dim, str) and ... in dim:
         dims_set: set[Hashable | ellipsis] = set(dim)
         all_dims_set = set(all_dims)
         if check_exists:

xarray/tests/test_utils.py

@@ -1,6 +1,6 @@
 from __future__ import annotations
 
-from collections.abc import Hashable, Iterable, Sequence
+from collections.abc import Hashable, Iterable
 
 import numpy as np
 import pandas as pd
@@ -297,7 +297,7 @@ def test_parse_dims_replace_none(dim: None | ellipsis) -> None:
         pytest.param(["x", 2], id="list_missing_all"),
     ],
 )
-def test_parse_dims_raises(dim: str | Iterable[Hashable]) -> None:
+def test_parse_dims_raises(dim):
     all_dims = ("a", "b", 1, ("b", "c"))  # selection of different Hashables
     with pytest.raises(ValueError, match="'x'"):
         utils.parse_dims(dim, all_dims, check_exists=True)
@@ -313,10 +313,7 @@ def test_parse_dims_raises(dim: str | Iterable[Hashable]) -> None:
         pytest.param(["a", ..., "b"], ("a", "c", "b"), id="list_with_middle_ellipsis"),
     ],
 )
-def test_parse_ordered_dims(
-    dim: str | Sequence[Hashable | ellipsis],
-    expected: tuple[Hashable, ...],
-) -> None:
+def test_parse_ordered_dims(dim, expected):
     all_dims = ("a", "b", "c")
     actual = utils.parse_ordered_dims(dim, all_dims)
     assert actual == expected