title: Python Pandas - Index' object has no attribute 'hour'
body: <p>I have a pandas dateframe and the following code works</p>
  
  <pre><code>df['hour'] = df.index.hour
  df['c'] = df['hour'].apply(circadian)
  </code></pre>
  
  <p>but i was trying to reduce the need to make a 'hour' coloumn, using the following code</p>
  
  <pre><code>df['c'] = df.apply(lambda x: circadian(x.index.hour), axis=1)
  </code></pre>
  
  <p>but I get the error message</p>
  
  <pre><code>AttributeError: ("'Index' object has no attribute 'hour'", u'occurred at index 2015-09-25 01:00:00')
  </code></pre>
  
  <p>anyone know how to do this?</p>