consolidate logic a bit

pandas-dev · TomAugspurger · Apr 23, 2018 · Mar 30, 2018 · Mar 30, 2018 · Mar 30, 2018
commit 97a2b06c305f70ffd0c1e4fcbce4169d1f54ccf9
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
@@ -1327,16 +1327,18 @@ def _set_names(self, values, level=None):
         ------
         TypeError if each name is not hashable.
         """
-        # GH 20527
-        # All items in 'name' need to be hashable:
-        if values is not None:
-            for name in values:
-                if not is_hashable(name):
-                    raise TypeError('{}.name must be a hashable type'
-                                    .format(self.__class__.__name__))
+        if not is_list_like(values):
+            raise ValueError('Names must be a list-like')
         if len(values) != 1:
             raise ValueError('Length of new names must be 1, got %d' %
                              len(values))
+
+        # GH 20527
+        # All items in 'name' need to be hashable:
+        for name in values:
+            if not is_hashable(name):
+                raise TypeError('{}.name must be a hashable type'
+                                .format(self.__class__.__name__))
         self.name = values[0]
 
     names = property(fset=_set_names, fget=_get_names)

diff --git a/pandas/core/indexes/multi.py b/pandas/core/indexes/multi.py
@@ -635,18 +635,29 @@ def _get_names(self):
 
     def _set_names(self, names, level=None, validate=True):
         """
+        Set new names on index. Each name has to be a hashable type.
+
+        Parameters
+        ----------
+        values : str or sequence
+            name(s) to set
+        level : int, level name, or sequence of int/level names (default None)
+            If the index is a MultiIndex (hierarchical), level(s) to set (None
+            for all levels).  Otherwise level must be None
+        validate : boolean, default True
+            validate that the names match level lengths
+
+        Raises
+        ------
+        TypeError if each name is not hashable.
+
+        Notes
+        -----
         sets names on levels. WARNING: mutates!
 
         Note that you generally want to set this *after* changing levels, so
         that it only acts on copies
         """
-        # GH 20527
-        # All items in 'names' need to be hashable:
-        for levels, name in enumerate(names):
-            if not is_hashable(name):
-                raise TypeError('{}.name must be a hashable type'
-                                .format(self.__class__.__name__))
-
         # GH 15110
         # Don't allow a single string for names in a MultiIndex
         if names is not None and not is_list_like(names):
@@ -669,10 +680,20 @@ def _set_names(self, names, level=None, validate=True):
 
         # set the name
         for l, name in zip(level, names):
-            if name is not None and name in used:
-                raise ValueError('Duplicated level name: "{}", assigned to '
-                                 'level {}, is already used for level '
-                                 '{}.'.format(name, l, used[name]))
+            if name is not None:
+
+                # GH 20527
+                # All items in 'names' need to be hashable:
+                if not is_hashable(name):
+                    raise TypeError('{}.name must be a hashable type'
+                                    .format(self.__class__.__name__))
+
+                if name in used:
+                    raise ValueError(
+                        'Duplicated level name: "{}", assigned to '
+                        'level {}, is already used for level '
+                        '{}.'.format(name, l, used[name]))
+
             self.levels[l].rename(name, inplace=True)
             used[name] = l