Fix inconsistent behaviour for xarray.DataArray.rename (#1178)

* Changes `DataArray.rename` to a more explicit behavior.

* Changes to only one argument for `DataArray.rename`.

* Rollback of argument name of `DataArray.rename`.

* Removes copy operation on dict, because it is no longer modified.

* Adds attribution.

doc/whats-new.rst

@@ -21,6 +21,11 @@ v0.9.0 (unreleased)
 Breaking changes
 ~~~~~~~~~~~~~~~~
 
+- ``DataArray.rename()`` behavior changed to strictly change the ``DataArray.name``
+  if called with string argument, or strictly change coordinate names if called with
+  dict-like argument.
+  By `Markus Gonser <https://github.com/magonser>`_.
+
 - By default ``to_netcdf()`` add a ``_FillValue = NaN`` attributes to float types.
   By `Frederic Laliberte <https://github.com/laliberte>`_.
 

xarray/core/dataarray.py

@@ -789,15 +789,16 @@ def reindex(self, method=None, tolerance=None, copy=True, **indexers):
         return self._from_temp_dataset(ds)
 
     def rename(self, new_name_or_name_dict):
-        """Returns a new DataArray with renamed coordinates and/or a new name.
+        """Returns a new DataArray with renamed coordinates or a new name.
 
 
         Parameters
         ----------
         new_name_or_name_dict : str or dict-like
             If the argument is dict-like, it it used as a mapping from old
-            names to new names for coordinates (and/or this array itself).
-            Otherwise, use the argument as the new name for this array.
+            names to new names for coordinates. Otherwise, use the argument
+            as the new name for this array.
+
 
         Returns
         -------
@@ -810,13 +811,8 @@ def rename(self, new_name_or_name_dict):
         DataArray.swap_dims
         """
         if utils.is_dict_like(new_name_or_name_dict):
-            name_dict = new_name_or_name_dict.copy()
-            if self.name in self.dims:
-                name = name_dict.get(self.name, self.name)
-            else:
-                name = name_dict.pop(self.name, self.name)
-            dataset = self._to_temp_dataset().rename(name_dict)
-            return self._from_temp_dataset(dataset, name)
+            dataset = self._to_temp_dataset().rename(new_name_or_name_dict)
+            return self._from_temp_dataset(dataset)
         else:
             return self._replace(name=new_name_or_name_dict)
 

xarray/test/test_dataarray.py

@@ -893,13 +893,7 @@ def test_rename(self):
             renamed.to_dataset(), self.ds.rename({'foo': 'bar'}))
         self.assertEqual(renamed.name, 'bar')
 
-        renamed = self.dv.rename({'foo': 'bar'})
-        self.assertDatasetIdentical(
-            renamed.to_dataset(), self.ds.rename({'foo': 'bar'}))
-        self.assertEqual(renamed.name, 'bar')
-
-        # regression to #1116
-        renamed = self.dv.x.rename({'x': 'z'})
+        renamed = self.dv.x.rename({'x': 'z'}).rename('z')
         self.assertDatasetIdentical(
             renamed, self.ds.rename({'x': 'z'}).z)
         self.assertEqual(renamed.name, 'z')