CLN: clean up type checking for MultiIndex indexing

closes #GH15452

Author: toobaz

pandas/core/frame.py

@@ -2214,7 +2214,7 @@ def query(self, expr, inplace=False, **kwargs):
 
         try:
             new_data = self.loc[res]
-        except ValueError:
+        except (ValueError, NotImplementedError):
             # when res is multi-dimensional loc raises, but this is sometimes a
             # valid query
             new_data = self[res]

pandas/core/indexing.py

@@ -1511,37 +1511,28 @@ def _getitem_axis(self, key, axis=0):
         elif is_bool_indexer(key):
             return self._getbool_axis(key, axis=axis)
         elif is_list_like_indexer(key):
+            if isinstance(key, ABCDataFrame):
+                # GH 15438
+                raise NotImplementedError("Indexing a with a DataFrame key is "
+                                          "not implemented")
+            elif hasattr(key, 'ndim') and key.ndim > 1:
+                raise NotImplementedError("Indexing with a multidimensional "
+                                          "key is not implemented")
 
             # convert various list-like indexers
             # to a list of keys
             # we will use the *values* of the object
             # and NOT the index if its a PandasObject
             if isinstance(labels, MultiIndex):
-
-                if isinstance(key, (ABCSeries, np.ndarray)) and key.ndim <= 1:
-                    # Series, or 0,1 ndim ndarray
+                if isinstance(key, (ABCSeries, np.ndarray)) and key.ndim != 1:
+                    # Series or 1-dim ndarray
                     # GH 14730
                     key = list(key)
-                elif isinstance(key, ABCDataFrame):
-                    # GH 15438
-                    raise NotImplementedError("Indexing a MultiIndex with a "
-                                              "DataFrame key is not "
-                                              "implemented")
-                elif hasattr(key, 'ndim') and key.ndim > 1:
-                    raise NotImplementedError("Indexing a MultiIndex with a "
-                                              "multidimensional key is not "
-                                              "implemented")
-
-                if (not isinstance(key, tuple) and len(key) > 1 and
-                        not isinstance(key[0], tuple)):
-                    key = tuple([key])
+                if not isinstance(key, tuple):
+                    return self._getitem_iterable(key, axis=axis)
 
             # an iterable multi-selection
-            if not (isinstance(key, tuple) and isinstance(labels, MultiIndex)):
-
-                if hasattr(key, 'ndim') and key.ndim > 1:
-                    raise ValueError('Cannot index with multidimensional key')
-
+            else:
                 return self._getitem_iterable(key, axis=axis)
 
             # nested tuple slicing