title: extract hour from timestamp with python
body: <p>I have a dataframe  df_energy2</p>
  
  <pre><code>df_energy2.info()
  &lt;class 'pandas.core.frame.DataFrame'&gt;
  RangeIndex: 29974 entries, 0 to 29973
  Data columns (total 4 columns):
  TIMESTAMP        29974 non-null datetime64[ns]
  P_ACT_KW         29974 non-null int64
  PERIODE_TARIF    29974 non-null object
  P_SOUSCR         29974 non-null int64
  dtypes: datetime64[ns](1), int64(2), object(1)
  memory usage: 936.8+ KB
  </code></pre>
  
  <p>with this structure :</p>
  
  <pre><code>df_energy2.head()
  
  TIMESTAMP P_ACT_KW PERIODE_TARIF P_SOUSCR
  2016-01-01 00:00:00 116 HC 250 
  2016-01-01 00:10:00 121 HC 250
  </code></pre>
  
  <p>Is there any python fucntion which can extract hour from <code>TIMESTAMP</code>?</p>
  
  <p>Kind regards</p>