r - Check existence of directory and create if doesn't exist

I often find myself writing R scripts that generate a lot of output. I find it cleaner to put this output into it's own directory(s). What I've written below will check for the existence of a directory and move into it, or create the directory and then move into it. Is there a better way to approach this?

mainDir <- "c:/path/to/main/dir"
subDir <- "outputDirectory"

if (file.exists(subDir)){
    setwd(file.path(mainDir, subDir))
} else {
    dir.create(file.path(mainDir, subDir))
    setwd(file.path(mainDir, subDir))

}

Answer

Use showWarnings = FALSE:

dir.create(file.path(mainDir, subDir), showWarnings = FALSE)
setwd(file.path(mainDir, subDir))

dir.create() does not crash if the directory already exists, it just prints out a warning. So if you can live with seeing warnings, there is no problem with just doing this:

dir.create(file.path(mainDir, subDir))
setwd(file.path(mainDir, subDir))