R programming r bind error

Question

My R function does the following:

• reads in the directory name 
• reads a particular set of numbers that represents the files
• combines the mentioned files into a data frame
• prints out the number of occurrences for a particular ID

Here's the function:

library(plyr)

complete <- function(directory, id=1:5){

  files_full <- list.files(directory, full.names=TRUE)
  working_set <- files_full [id]
  seethis <- lapply(working_set, read.csv)
  output <- do.call(rbind, seethis)

  no_na <- na.omit(output)
  new_df <- as.data.frame(no_na)
  new_output <- count(new_df,"ID")
  colnames(new_output) <- c("id", "Occurrences")
  new_output
}

Now, If the function is invoked with

complete("diet_data",c(4,3,2))

I get the following:

  id Occurrences
1  2          30
2  3          17
3  4          30

But I wish to retain the id order, i.e. 4, 3, 2 so that output is

  id Occurrences
1  4          30
2  3          17
3  2          30

How to do this? And there is no way to tell if id will be 1:5, 5:3, etc

Answer 1

Add this line at the end of your R function:

sorted_output <- new_output[match(id, new_output$ID),]

Answer 2

You can use arrange function at last line like below.

new_output %>% arrange(-id)