Add Dataset.drop_dims()

* Drops full dimensions and any corresponding variables in a
  Dataset

Author: kmsquire

xarray/core/dataset.py

@@ -2797,6 +2797,41 @@ def _drop_vars(self, names):
         coord_names = set(k for k in self._coord_names if k in variables)
         return self._replace_vars_and_dims(variables, coord_names)
 
+    def drop_dims(self, drop_dims, inplace=False):
+        """Drop dimensions from a Dataset.  Any data variables containing
+           these dimensions will also be dropped.
+
+        Parameters
+        ----------
+        drop_dims : str or list
+            Dimension or dimensions to drop.
+        inplace : bool, optional
+            If True, modify this dataset inplace. Otherwise, create a new
+            object.
+
+        Returns
+        -------
+        obj : Dataset
+            A dataset without the given dimensions (or any variables
+            containing those dimensions)
+        """
+        if utils.is_scalar(drop_dims):
+            drop_dims = [drop_dims]
+
+        missing_dimensions = [d for d in drop_dims if d not in self.dims]
+        if missing_dimensions:
+            raise ValueError('Dataset does not contain the dimensions: %s'
+                             % missing_dimensions)
+
+        drop_vars = set(k for k, v in self._variables.items()
+                        for d in v.dims if d in drop_dims)
+
+        variables = OrderedDict((k, v) for k, v in self._variables.items()
+                                if k not in drop_vars)
+        coord_names = set(k for k in self._coord_names if k in variables)
+
+        return self._replace_with_new_dims(variables, coord_names, inplace=inplace)
+
     def transpose(self, *dims):
         """Return a new Dataset object with all array dimensions transposed.
 

xarray/tests/test_dataset.py

@@ -1863,6 +1863,41 @@ def test_drop_index_labels(self):
                 ValueError, 'does not have coordinate labels'):
             data.drop(1, 'y')
 
+    def test_drop_dims(self):
+        data = xr.Dataset({'A': (['x', 'y'], np.random.randn(2, 3)),
+                           'B': ('x', np.random.randn(2)),
+                           'x': ['a', 'b'], 'z': np.pi})
+
+        actual = data.drop_dims('x')
+        expected = data.drop(['A','B','x'])
+        assert_identical(expected, actual)
+
+        actual = data.drop_dims('y')
+        expected = data.drop('A')
+        assert_identical(expected, actual)
+
+        actual = data.drop_dims(['x','y'])
+        expected = data.drop(['A','B','x'])
+        assert_identical(expected, actual)
+
+        actual = data.copy()
+        actual.drop_dims('y', inplace=True)
+        expected = data.drop('A')
+        assert_identical(expected, actual)
+
+        actual = data.copy()
+        actual.drop_dims('x', inplace=True)
+        expected = data.drop(['A','B','x'])
+        assert_identical(expected, actual)
+
+        actual = data.copy()
+        actual.drop_dims(['x','y'], inplace=True)
+        expected = data.drop(['A','B','x'])
+        assert_identical(expected, actual)
+
+        with pytest.raises((ValueError, KeyError)):
+            data.drop_dims('z')  # not a dimension
+
     def test_copy(self):
         data = create_test_data()