Convert Variable to IndexVariable when renamed to existing dim name

Author: dcherian

xarray/core/dataset.py

@@ -2782,6 +2782,17 @@ def _rename_all(self, name_dict, dims_dict):
         variables, coord_names = self._rename_vars(name_dict, dims_dict)
         dims = self._rename_dims(dims_dict)
         indexes = self._rename_indexes(name_dict, dims.keys())
+
+        # Variable could be renamed to an existing dimension name
+        # in this case, convert to IndexVariable and set indexes
+        # GH4107
+        for name in coord_names:
+            indexvar = variables.pop(name).to_index_variable()
+            variables[name] = indexvar
+            if indexes is None:
+                indexes = dict()
+            indexes[name] = indexvar.to_index()
+
         return variables, coord_names, dims, indexes
 
     def rename(

xarray/tests/test_dataset.py

@@ -2558,6 +2558,14 @@ def test_rename_vars(self):
         with pytest.raises(ValueError):
             original.rename_vars(names_dict_bad)
 
+    def test_rename_to_dim_name(self):
+        # regression test for GH4107
+        coord_1 = xr.DataArray([1, 2], dims=["coord_1"], attrs={"attrs": True})
+        ds = xr.Dataset()
+        ds["a"] = xr.DataArray([1, 0], [coord_1])
+        obj = ds.reset_index("coord_1").rename({"coord_1_": "coord_1"})
+        assert_equal(ds, obj)
+
     def test_rename_multiindex(self):
         mindex = pd.MultiIndex.from_tuples(
             [([1, 2]), ([3, 4])], names=["level0", "level1"]