Add mapping-style get method to CF accessors

cf_xarray/accessor.py

@@ -172,6 +172,7 @@ def __repr__(self) -> str:
 
 # Type for decorators
 F = TypeVar("F", bound=Callable[..., Any])
+T_Default = TypeVar("T_Default")
 
 
 def sort_maybe_hashable(iterable: Iterable[Hashable]) -> list[Hashable]:
@@ -1544,6 +1545,38 @@ def __init__(self, obj):
     def __setstate__(self, d):
         self.__dict__ = d
 
+    @overload
+    def get(
+        self, key: Hashable | Iterable[Hashable], default: None = None
+    ) -> DataArray | Dataset | None: ...
+
+    @overload
+    def get(
+        self, key: Hashable | Iterable[Hashable], default: T_Default
+    ) -> DataArray | Dataset | T_Default: ...
+
+    def get(self, key: Hashable | Iterable[Hashable], default=None):
+        """
+        Access a variable using CF attributes, returning a default if not found.
+
+        Parameters
+        ----------
+        key : Hashable or Iterable of Hashable
+            Key passed to ``__getitem__``.
+        default : Any, optional
+            Value to return when ``key`` is not found.
+
+        Returns
+        -------
+        DataArray, Dataset, or Any
+            The object selected by ``key``, or ``default`` if selection raises
+            ``KeyError``.
+        """
+        try:
+            return self[key]  # type: ignore[index]
+        except KeyError:
+            return default
+
     def _assert_valid_other_comparison(self, other):
         # TODO cache this property
         flag_dict = create_flag_dict(self._obj)

cf_xarray/tests/test_accessor.py

@@ -692,6 +692,22 @@ def test_getitem_errors(obj):
         obj2.cf["X"]
 
 
+@pytest.mark.parametrize("obj", objects)
+def test_get(obj):
+    assert_identical(obj.cf.get("longitude"), obj.cf["longitude"])
+    assert obj.cf.get("missing") is None
+
+    default = object()
+    assert obj.cf.get("missing", default) is default
+
+
+def test_get_iterable_key():
+    assert_identical(airds.cf.get(["longitude"]), airds.cf[["longitude"]])
+
+    default = object()
+    assert airds.air.cf.get(["longitude"], default) is default
+
+
 def test_bad_cell_measures_attribute() -> None:
     air2 = airds.copy(deep=False)
     air2.air.attrs["cell_measures"] = "--OPT"