title: How to group rows by column name and sort rows by datetime
body: <p>I need to order rows by date and time grouping them by <code>ID</code>:</p>
  
  <pre><code>df =
  
  ID   TYPE  DATETIME
  1    A     12/18/2015 23:02:00
  1    A     12/17/2015 12:00:09
  1    A     12/18/2015 18:04:08
  2    B     12/20/2015 15:03:05
  2    B     12/18/2015 14:02:07
  </code></pre>
  
  <p>The result should be this one:</p>
  
  <p>result =</p>
  
  <pre><code>ID   TYPE  DATETIME
  1    A     12/17/2015 12:00:09
  1    A     12/18/2015 18:04:08
  1    A     12/18/2015 23:02:00
  2    B     12/18/2015 14:02:07
  2    B     12/20/2015 15:03:05
  </code></pre>
  
  <p>How can I do it?</p>
  
  <pre><code>df.groupby("ID").sort(...)
  </code></pre>