title: Difference between timestamps as days
body: <p>I am trying to create a column with the difference between two timestamps. The difference should be represented as days.</p>
  <pre><code>data = {'date1':['2020-12-01 00:00:00', '2020-12-09 00:00:00']}
  df = pd.DataFrame(data)
  df['date1'] = pd.to_datetime(df['date1'])
  
  benchmark=pd.Timestamp('2020-12-11 00:00:00')
  benchmark-df['date1']
  </code></pre>
  <p>Output:</p>
  <pre><code>0   10 days
  1    2 days
  Name: date1, dtype: timedelta64[ns]
  </code></pre>
  <p>The above gives the difference as a Timedelta, from which the days can be extracted - is there a shorter and efficient way to get the days as an int other than iterating over each row to extract the days attribute?</p>