代码如下，
> x<-rbind(matrix(rnorm(4,sd=0.3),ncol=2),matrix(rnorm(4,mean=1,sd=0.3),ncol=2))
> ww <- c(4,0)
> x1 <- x[,ww!=0]
> z<-sweep(x1,2,sqrt(ww[ww!=0]),"*")
Error in array(STATS, dims[perm]) : 'dims' cannot be of length 0
并且traceback（）显示
> traceback()
3: array(STATS, dims[perm])
2: aperm(array(STATS, dims[perm]), order(perm))
1: sweep(x1, 2, sqrt(ww[ww != 0]), "*")
那么为什么会出现错误以及如何解决？