title: Change from date and hour format to numeric format
body: <p>I am working in R and I need to change from a column in format </p>
  
  <pre><code>9/27/2011  3:33:00 PM 
  </code></pre>
  
  <p>to a value format. In Excel I can use the function <code>value()</code> but I do not know how to do it in R.</p>
  
  <p>My data looks like this:</p>
  
  <pre><code>9/27/2011 15:33 a   1   5   9
  9/27/2011 15:33 v   2   6   2
  9/27/2011 15:34 c   3   7   1
  </code></pre>