fix adding coords/vars with the same name than a multi-index level

Author: Benoit Bovy

xarray/core/coordinates.py

@@ -151,6 +151,12 @@ def to_dataset(self):
     def _update_coords(self, coords):
         from .dataset import calculate_dimensions
 
+        for key in coords:
+            if key in self._data._level_coords:
+                raise ValueError("%r is already a MultiIndex level of "
+                                 "coordinate %r"
+                                 % (key, self._data._level_coords[key]))
+
         variables = self._data._variables.copy()
         variables.update(coords)
 
@@ -197,6 +203,12 @@ def _names(self):
     def _update_coords(self, coords):
         from .dataset import calculate_dimensions
 
+        for key in coords:
+            if key in self._data._level_coords:
+                raise ValueError("%r is already a MultiIndex level of "
+                                 "coordinate %r"
+                                 % (key, self._data._level_coords[key]))
+
         dims = calculate_dimensions(coords)
         if set(dims) != set(self.dims):
             raise ValueError('cannot add coordinates with new dimensions to '

xarray/core/dataarray.py

@@ -69,7 +69,6 @@ def _infer_coords_and_dims(shape, coords, dims):
             new_coords[dim] = default_index_coordinate(dim, size)
 
     sizes = dict(zip(dims, shape))
-    level_names = {}
     for k, v in new_coords.items():
         if any(d not in dims for d in v.dims):
             raise ValueError('coordinate %s has dimensions %s, but these '

xarray/core/dataset.py

@@ -565,6 +565,12 @@ def __setitem__(self, key, value):
         if utils.is_dict_like(key):
             raise NotImplementedError('cannot yet use a dictionary as a key '
                                       'to set Dataset values')
+
+        if key in self._level_coords:
+            raise ValueError("%r is already a MultiIndex level of "
+                             "coordinate %r"
+                             % (key, self._level_coords[key]))
+
         self.update({key: value})
 
     def __delitem__(self, key):