For循环适用于前10个文件，但随后出现错误

我试图编写一个函数：

pollutantmean<-function(directory,pollutant,id=1:332){
  meanpollut<-matrix(nrow = length(id),ncol = 1)
  for (i in id) {
    data<-read.csv(dir()[i])
    test<-data[,pollutant]
    meanpollut[i,]<-mean(test,na.rm = TRUE)
  }
  m<-mean(meanpollut)
  m
}

但是当我试着运行这个

pollutantmean("specdata", "nitrate", 70:72)

我得到这个错误：

Error in `[<-`(`*tmp*`, i, , value = mean(test, na.rm = TRUE)) : 
  subscript out of bounds

---

“[中的

错误我们可以使用
seq\u沿
而不是id中的
i

pollutantmean<-function(directory,pollutant,id=1:332){
  meanpollut<-matrix(nrow = length(id),ncol = 1)
  for (i in seq_along(id)) {
    data<-read.csv(dir()[id[i]])
    test<-data[,pollutant]
    meanpollut[i,]<-mean(test,na.rm = TRUE)
  }
  m<-mean(meanpollut)
  m
}

pollutantmeanUnderstand.我成功地得到了答案，谢谢！
data<-read.csv(dir()[70])
> test<-data[,"nitrate"]
> mean(test,na.rm = TRUE)

pollutantmean<-function(directory,pollutant,id=1:332){
  meanpollut<-matrix(nrow = length(id),ncol = 1)
  for (i in seq_along(id)) {
    data<-read.csv(dir()[id[i]])
    test<-data[,pollutant]
    meanpollut[i,]<-mean(test,na.rm = TRUE)
  }
  m<-mean(meanpollut)
  m
}