PERF: Use generator expression instead of list comprehension.

Author: ssanderson

pandas/core/index.py

@@ -324,7 +324,7 @@ def _coerce_to_ndarray(cls, data):
 
     def _get_attributes_dict(self):
         """ return an attributes dict for my class """
-        return dict([ (k,getattr(self,k,None)) for k in self._attributes])
+        return dict((k, getattr(self, k, None)) for k in self._attributes)
 
     def view(self, cls=None):