nd-rolling

xarray/core/rolling.py

@@ -100,10 +100,7 @@ def __repr__(self):
 
         attrs = [
             "{k}->{v}".format(k=k, v=getattr(self, k))
-            for k in list(self.dim)
-            + list(self.window)
-            + list(self.center)
-            + [self.min_periods]
+            for k in list(self.dim) + self.window + self.center + [self.min_periods]
         ]
         return "{klass} [{attrs}]".format(
             klass=self.__class__.__name__, attrs=",".join(attrs)
@@ -272,12 +269,9 @@ def construct(
 
         from .dataarray import DataArray
 
-        if window_dim is None:
-            if len(window_dim_kwargs) == 0:
-                raise ValueError(
-                    "Either window_dim or window_dim_kwargs need to be specified."
-                )
-            window_dim = {d: window_dim_kwargs[d] for d in self.dim}
+        window_dim = utils.either_dict_or_kwargs(
+            window_dim, window_dim_kwargs, "Dataset.rolling"
+        )
 
         window_dim = self._mapping_to_list(
             window_dim, allow_default=False, allow_allsame=False

xarray/tests/test_dataset.py

@@ -6008,15 +6008,25 @@ def test_rolling_reduce(ds, center, min_periods, window, name):
 @pytest.mark.parametrize("ds", (1,), indirect=True)
 @pytest.mark.parametrize("center", (True, False))
 @pytest.mark.parametrize("min_periods", (None, 1))
-@pytest.mark.parametrize("name", ("sum", "mean", "max"))
+@pytest.mark.parametrize("name", ("sum", "mean", "max", "std"))
 def test_ndrolling_reduce(ds, center, min_periods, name):
-    rolling_obj = ds.rolling(time=3, x=2, center=center, min_periods=min_periods)
+    rolling_obj = ds.rolling(time=4, x=3, center=center, min_periods=min_periods)
 
     actual = getattr(rolling_obj, name)()
     expected = getattr(
         getattr(
-            ds.rolling(time=3, center=center, min_periods=min_periods), name
-        )().rolling(x=2, center=center, min_periods=min_periods),
+            ds.rolling(time=4, center=center, min_periods=min_periods), name
+        )().rolling(x=3, center=center, min_periods=min_periods),
+        name,
+    )()
+    assert_allclose(actual, expected)
+    assert actual.dims == expected.dims
+
+    # Do it in the oposite order
+    expected = getattr(
+        getattr(
+            ds.rolling(x=3, center=center, min_periods=min_periods), name
+        )().rolling(time=4, center=center, min_periods=min_periods),
         name,
     )()