@Substitution(name='<STR_LIT>')<EOL><INDENT>@Substitution(see_also=_common_see_also)<EOL>def head(self, n=<NUM_LIT:5>):<DEDENT>
self._reset_group_selection()<EOL>mask = self._cumcount_array() < n<EOL>return self._selected_obj[mask]<EOL>
Return first n rows of each group.

Essentially equivalent to ``.apply(lambda x: x.head(n))``,
except ignores as_index flag.
%(see_also)s
Examples
--------

>>> df = pd.DataFrame([[1, 2], [1, 4], [5, 6]],
                      columns=['A', 'B'])
>>> df.groupby('A', as_index=False).head(1)
   A  B
0  1  2
2  5  6
>>> df.groupby('A').head(1)
   A  B
0  1  2
2  5  6