相关疑难解决方法(0)

我有dataframe dih_y2.这两行给了我一个警告:

> memb = dih_y2$MemberID[1:10]
> dih_col = which(dih_y2$MemberID == memb)  
Warning message:
In dih_y2$MemberID == memb :
longer object length is not a multiple of shorter object length

为什么？