title: How to obtain a list of directories within a directory, like list.files(), but instead "list.dirs()"
body: <p>This may be a very easy question for someone - I am able to use <code>list.files()</code> to obtain a list of files in a given directory, but if I want to get a list of directories, how would I do this?  Is it somehow right in front of me as an option within <code>list.files()</code>?</p>
  
  <p>Also, I'm using Windows, so if the answer is to shell out to some Linux/unix command, that won't work for me.</p>
  
  <p>.NET for example has a <code>Directory.GetFiles()</code> method, and a separate <code>Directory.GetDirectories()</code>
  method, so I figured R would have an analogous pair. Thanks in advance.</p>