NLASTANIEM SERII HIERARCHY PANDA
print (grouped.groupby(level='yearmonth').nlargest(3).reset_index(level=0, drop=True))
yearmonth product
201601 E 180
A 100
B 90
201602 F 220
A 200
C 120
201603 B 120
C 110
D 110
Name: val, dtype: int64
Joyous Jaguar