Merge branch 'master' of https://github.com/akloster/pandas into akloster-master

Author: jreback

pandas/core/internals.py

@@ -1881,8 +1881,8 @@ def set_axis(self, axis, value, maybe_rename=True, check_axis=True):
         value = _ensure_index(value)
 
         if check_axis and len(value) != len(cur_axis):
-            raise ValueError('Length mismatch (%d vs %d)'
-                            % (len(value), len(cur_axis)))
+            raise ValueError('Length mismatch: Expected axis has %d elements, new values have %d elements'
+                            % (len(cur_axis), len(value)))
 
         self.axes[axis] = value
         self._shape = None
@@ -3361,9 +3361,9 @@ def set_axis(self, axis, value):
         value = _ensure_index(value)
 
         if len(value) != len(cur_axis):
-            raise Exception('Length mismatch (%d vs %d)'
-                            % (len(value), len(cur_axis)))
-        self.axes[axis] = value
+            raise ValueError('Length mismatch: Expected axis has %d elements, new values have %d elements'
+                            % (len(cur_axis), len(value)))
+
         self._shape = None
         self._block.set_ref_items(self.items, maybe_rename=True)