Fourth?

Author: rhshadrach

pandas/core/groupby/groupby.py

@@ -2629,7 +2629,10 @@ def head(self, n=5):
         """
         self._reset_group_selection()
         mask = self._cumcount_array() < n
-        return self._selected_obj[mask]
+        if self.axis == 1:
+            return self._selected_obj.T[mask].T
+        else:
+            return self._selected_obj[mask]
 
     @Substitution(name="groupby")
     @Substitution(see_also=_common_see_also)
@@ -2663,7 +2666,10 @@ def tail(self, n=5):
         """
         self._reset_group_selection()
         mask = self._cumcount_array(ascending=False) < n
-        return self._selected_obj[mask]
+        if self.axis == 1:
+            return self._selected_obj.T[mask].T
+        else:
+            return self._selected_obj[mask]
 
     def _reindex_output(
         self, output: OutputFrameOrSeries, fill_value: Scalar = np.NaN

pandas/core/groupby/ops.py

@@ -211,6 +211,18 @@ def apply(self, f: F, data: FrameOrSeries, axis: int = 0):
             # group might be modified
             group_axes = group.axes
             res = f(group)
+            print('res:')
+            print(res.index)
+            print()
+            print('group_axes:')
+            print(group_axes[0])
+            print()
+            print('new1:')
+            print(res.axes[axis])
+            print()
+            print('new2:')
+            print(group_axes[axis])
+            print()
             if not _is_indexed_like(res, group_axes):
                 mutated = True
             result_values.append(res)