title: Convert column of date objects in Pandas DataFrame to strings
body: <p>How to convert a column consisting of datetime64 objects to a strings that would read
  01-11-2013 for today's date of November 1.</p>
  
  <p>I have tried </p>
  
  <pre><code>df['DateStr'] = df['DateObj'].strftime('%d%m%Y')
  </code></pre>
  
  <p>but I get this error</p>
  
  <p><strong>AttributeError: 'Series' object has no attribute 'strftime'</strong></p>