Question

I have written a function, which takes some time to run (due to a 1000+ loop on a huge dataset in combination with forecasting model testing).

To have any idea on the status, while the function is called, I use the message command inside the for-loop in the function. The problem is that all the messages are shown in the console after the function is finished, instead of showing immediately. So it doesn’t help me 🙂

I tried to find a solution on Stackoverflow, but didn’t found one. I looked for instance on the question “showing a status message in R“. All answers and example codes in that topic still give me only text in the console after a function is processed instead of immediately.

How to solve this? Is there maybe a setting in R which prevents immediate printing of message text in the console?

note: examples I tried below, which give the same results as my function; showing text after processing the function.

example1 (Joshua Ulrich):

for(i in 1:10) {
  Sys.sleep(0.2)
  # Dirk says using cat() like this is naughty ;-)
  #cat(i,"\r")
  # So you can use message() like this, thanks to Sharpie's
  # comment to use appendLF=FALSE.
  message(i,"\r",appendLF=FALSE)
  flush.console()
}

example2 (Tyler):

test.message <- function() {
  for (i in 1:9){
    cat(i)
    Sys.sleep(1)
    cat("\b")
  }
}

edit: the first example does work (‘flush console’ was the problem)…but when I tested it, I commented out flush console for some reason :S

Answer 1

test.message <- function() {
     for (i in 1:9){
       cat(paste(as.character(i),'\n'))
       flush.console()
       Sys.sleep(1)
     }
   }

which is similar to the recommendation by fotNelton.

Edit: ttmaccer is most likely right. I’ve just tested on a Ubuntu server and the code works without flushing the console.