例如:
data = {'Platoon': ['A','A','A','A','A','A','B','B','B','B','B','C','C','C','C','C'],
'Date' : [1,2,3,4,5,6,1,2,3,4,5,1,2,3,4,5],
'Casualties': [1,4,5,7,5,5,6,1,4,5,6,7,4,6,4,6]}
df = pd.DataFrame(data)
下面的代码可以计算滚动平均值,包括当前行:
df['avg'] = df.groupby(['Platoon'])['Casualties'].transform(lambda x: x.rolling(2, 1).mean())
这意味着:
Platoon Date Casualties Avg
A 1 1 1.0
A 2 4 2.5
A 3 5 4.5
A 4 7 6.0
......
What I want to get is:
Platoon Date Casualties Avg
A 1 1 1.0
A 2 4 1.0
A 3 5 2.5
A 4 7 4.5
......
我猜这里可以使用 shift,但我想不出怎么做!