问我想在for循环代码中使用列表。list[[i]]工作得很好，但是为什么res <- vector("list"，n)不能工作呢？

EN

x <- matrix(rnorm(1806),7,258)
x2 <- matrix(rnorm(1032),4,258)

samp_size <- 3
iter <- 1000
subs <- matrix(sample(1:nrow(x), samp_size*iter, replace=T),
               ncol=samp_size, byrow=T)
subs2 <- matrix(sample(1:nrow(x2), samp_size*iter, replace=T),
                ncol=samp_size, byrow=T)

for(j in 1:nrow(subs)){
  ad <- x[subs[j,],]
  ad1 <- x2[subs2[j,],]
  rd <- rbind(ad,ad1)
  dis <- dist(rd, method="euclidian")
  #CV <- sd(unlist(rd), na.rm=TRUE)/mean(unlist(rd), na.rm=TRUE)*100
  dis2 <- dis[dis!=0]
  list[[j]] <- mean(dis2)
  l <- unlist(list)
  l <- na.omit(l)
  sdis <- dist(ad, method="euclidian")
  sdis2 <- sdis[sdis!=0]
  res <- vector("list", 1000)
  res[[j]] <- mean(sdis2)
  l2 <- unlist(res)
  l2 <- na.omit(l2)
}