Do not return <this-array> instances (#180)

Author: aulemahal

cf_xarray/accessor.py

@@ -351,7 +351,7 @@ def _get_with_standard_name(
 
     varnames = []
     if isinstance(obj, DataArray):
-        obj = obj._to_temp_dataset()
+        obj = obj.coords.to_dataset()
     for vname, var in obj.variables.items():
         stdname = var.attrs.get("standard_name", None)
         if stdname == name:

cf_xarray/tests/test_accessor.py

@@ -185,6 +185,10 @@ def test_getitem_standard_name():
     expected = airds["air"]
     assert_identical(actual, expected)
 
+    actual = airds.lat.cf["latitude"]
+    expected = airds["lat"]
+    assert_identical(actual, expected)
+
     ds = airds.copy(deep=True)
     ds["air2"] = ds.air
     with pytest.raises(KeyError):