title: R duplicate ID variables with different values
body: <p>I have a data frame that looks like this;</p>
  
  <pre><code>head(x)
  user_id    location
  1          New York
  1          Chicago
  2          Atlanta
  3          San Antonio
  </code></pre>
  
  <p>I would like to remove the duplicate rows (ie. user_id 1) without regard to their location. So I need a new data frame that only has unique ID's but still has ONE of their locations ( so for ID 1, it doesn't matter if it gets Chicago or New York).</p>