让我们将set_index和sum与参数level一起使用:

Let's use set_index and sum with argument level:

df['date'] = pd.to_datetime(df['date'])
df['Month'] = df['date'].dt.strftime('%b')
df['Day'] = df['date'].dt.day   
df.set_index(['Month','Day']).sum(level=[0,1]).reset_index()

输出:

  Month  Day  Revenue  Cost
0   Jun    1      600   120
1   Jun   20      400    80
2   May   21      500   100