R中的数据帧头是错误的

Question

I wrote a function that is supposed to return a dataframe. Although the output is fine, the headers of the output are incorrect. When I initialized the dataframe (output), I clearly labeled the two columns are 'id' and 'nobs'. However, in the output, the columns are labeled X30 and X932, respectively. Can someone help?

Here's my code

complete <- function(directory, id) {
  output <- data.frame(id=character(),
                   nobs=character(), 
                   stringsAsFactors=FALSE)
  files <- list.files()
  for (i in id){
  mydata <- read.csv(files[i])
  nobs <- nrow(na.omit(mydata))
  tempVector <- c(i, nobs)
  output <- rbind(output, tempVector)
}

print(output)

}

Answer 1

I can't test without a reproducible example, but if you do tempVector <- data.frame(id=i, nobs=nobs) , I think it will work the way you desire.

Or, you can save a few lines of code and do:

  mydata <- read.csv(files[i])
  output <- rbind(output, data.frame(id=i, nobs=nrow(na.omit(mydata))))

Answer 2

If i am correct you just want to know the id and the number of observations within this id.
Try readLines instead.

id <- 1:3
files <- list.files()
files_nrow <- function(id){
  c(id=id, nobs= length(readLines(files[id])))
}

data.frame(t(sapply(id,files_nrow)))

Result:

  id nobs
1  1   12
2  2   8
3  3   13