Question

I like to do use this in my scripts:

cat("Saving...")
do_something_slow()
cat("\rSaved\n")

The problem is that the carriage return is applied without erasing the rest of the line, so I get this:

Savedg...

To fix it I can do:

cat("\rSaved\033[K\n")

but it’s kind of ugly. Is there a simpler way?

Answer 1

I like to use message() instead of cat() for generating messages. For example:

cat("Saving..."); cat("\rSaved\n")

returns:

Savdg...

While:

message("Saving..."); message("\rSaved\n")

returns:

Saving...
Saved

Edit:

Inspired by @gauden answer, another function could be:

replaceMessage <- function(x, width = 80)
{
    message("\r", rep(" ", times = width - length(x)), "\r", appendLF = F)
    message(x, appendLF = F)
}

And then:

replaceMessage("Saving..."); Sys.sleep(1); replaceMessage("Saved\n")

Note:

While replaceMessage() behaves as expected in Linux and Rterm on Windows, it behaves strangely in my Rgui (2.15.0, Windows x64). Specifically, Saving... is never displayed, and after Saved is displayed, the cursor is moved width spaces (in the example, 80 spaces) to the right. I am not sure why.