BUG: add test case for integer index failure re: #819

Author: wesm

pandas/core/groupby.py

@@ -1115,14 +1115,13 @@ def aggregate(self, arg, *args, **kwargs):
                 raise ValueError('Can only pass dict with axis=0')
 
             obj = self._obj_with_exclusions
-            # more kludge
-            if len(obj.columns) == 1:
-                series_obj = Series(obj.ix[:,0])
-                series_name = obj.columns[0]
-                for col, func in arg.iteritems():
-                    colg = SeriesGroupBy(series_obj, column=series_name,
+
+            if self._column is not None:
+                series_obj = Series(obj[self._column])
+                for fname, func in arg.iteritems():
+                    colg = SeriesGroupBy(series_obj, column=self._column,
                                          grouper=self.grouper)
-                    result[col] = colg.aggregate(func)
+                    result[fname] = colg.aggregate(func)
             else:
                 for col, func in arg.iteritems():
                     colg = SeriesGroupBy(obj[col], column=col,

pandas/tests/test_groupby.py

@@ -710,6 +710,12 @@ def test_groupby_as_index_agg(self):
         result3 = grouped['C'].agg({'Q' : np.sum})
         assert_frame_equal(result3, expected3)
 
+    def test_multifunc_select_col_integer_cols(self):
+        df = self.df
+        df.columns = np.arange(len(df.columns))
+
+        # it works!
+        result = df.groupby(1, as_index=False)[2].agg({'Q' : np.mean})
 
     def test_as_index_series_return_frame(self):
         grouped = self.df.groupby('A', as_index=False)