通过 transform() :

def first_last_0(x):
    x.iloc[0] = 0 
    x.iloc[-1] = 0
    return x

df['Value'] = df.groupby('Category')['Value'].transform(first_last_0)

0       0
1     200
2      20
3       0
4       0
5     210
6       0
7       0
8     370
9       0
10      0
11     92
12      0
13      0
14     77
15      0