title: Check existence of directory and create if doesn't exist
body: <p>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?</p>
  
  <pre><code>mainDir &lt;- "c:/path/to/main/dir"
  subDir &lt;- "outputDirectory"
  
  if (file.exists(subDir)){
      setwd(file.path(mainDir, subDir))
  } else {
      dir.create(file.path(mainDir, subDir))
      setwd(file.path(mainDir, subDir))
  
  }
  </code></pre>