title: How to convert times over 24:00:00 in R
body: <p>In R I have this data.frame</p>
  
  <pre><code>24:43:30 23:16:02 14:05:44 11:44:30 ...
  </code></pre>
  
  <p>Note that some of the times are <strong>over</strong> 24:00:00 ! In fact all my times are within <code>02:00:00</code> to <code>25:59:59</code>.</p>
  
  <p>I want to subtract all entries in my dataset <code>data</code> with 2 hours. This way I get a regular data-set. How can I do this?</p>
  
  <p>I tried this </p>
  
  <pre><code>strptime(data, format="%H:%M:%S") - 2*60*60
  </code></pre>
  
  <p>and this work for all entries below <code>23:59:59</code>. For all entries above I simply get <code>NA</code> since the <code>strptime</code> command produce <code>NA</code> to all entries above <code>23:59:59</code>.</p>