title: how to extract days as integers from a timedelta64[ns] object in python
body: <p>I have a pandas dataframe with a column like:</p>
  
  <pre><code>In [96]: data['difference']
  Out[96]: 
  0                 NaT
  1     1 days 21:34:30
  2     0 days 16:57:36
  3     0 days 00:16:51
  4     0 days 15:52:38
  5     0 days 14:19:34
  6     0 days 02:54:46
  7     1 days 04:21:28
  8     0 days 01:58:55
  9     0 days 10:30:35
  10    0 days 07:53:04
  ....
  Name: difference, dtype: timedelta64[ns]
  </code></pre>
  
  <p>I want to create next to it a column with integers corresponding to the days values in this column.</p>