r - R：循环列表中的值

Question

我希望我的循环使用计算值作为索引，但它似乎不允许我这样做。

这是一个示例代码：

stype_rep <- c(6:10,11:15,31:35)

rep <- 6 #this can change


for (rep in stype_rep){

  print(sprintf("rep start loop: %s",rep))
  rep <- rep + 6 #this can change
  print(sprintf("rep added: %s", rep))

}

运行代码时，它没有使用 is 的新rep值rep + 6。我怎么做？

迪西

标签： rfor-loop

Answer 1

要在循环vector外递归更改for，您需要使用索引。请看下面的代码：

rep <- c(6:10, 11:15, 31:35)

for (i in seq_along(rep)[-1] - 1){
  print(sprintf("rep start loop: %s",rep[i]))
  rep[i + 1] <- rep[i] + 6 #this can change
  print(sprintf("rep added: %s",rep[i]))
}

输出：

[1] "rep start loop: 6"
[1] "rep added: 6"
[1] "rep start loop: 12"
[1] "rep added: 12"
[1] "rep start loop: 18"
[1] "rep added: 18"
[1] "rep start loop: 24"
[1] "rep added: 24"
[1] "rep start loop: 30"
[1] "rep added: 30"
[1] "rep start loop: 36"