title: Extract day and month from a datetime object
body: <p>I have a column with dates in string format <code>'2017-01-01'</code>. Is there a way to extract day and month from it using pandas?</p>
  
  <p>I have converted the column to <code>datetime dtype</code> but haven't figured out the later part: </p>
  
  <pre><code>df['Date'] =  pd.to_datetime(df['Date'], format='%Y-%m-%d')
  
  df.dtypes: 
  Date        datetime64[ns]
  
  print(df)
  
           Date
  0   2017-05-11
  1   2017-05-12
  2   2017-05-13 
  </code></pre>