title: Changing date format to "%d/%m/%Y"
body: <p>Would like to change the date format. My data frame is shown below and would like to change all the date formats to <code>"%d/%m/%Y"</code>.</p>
  
  <p>df:</p>
  
  <pre><code>id    bdate       wdate        ddate
  1   09/09/09    12/10/09     2009-09-27
  </code></pre>