我尝试仅过滤观察到的第一个 type=="y" 值。
df<-data.frame(id=c(1,1,1,1,2,2,2,2,2,3,3,3,3,3,3,3,3,3),
type=c("x","x","y","x","x","x","x","y","y","x","x","x","x","y","x","y","x","x"))
期望的输出：
id type
1 x
1 x
1 y
2 x
2 x
2 x
2 y
3 x
3 x
3 x
3 x
3 y
我用代码尝试一下：
id type
1 x
1 x
1 y
2 x
2 x
2 x
2 y
3 x
3 x
3 x
3 x
3 y