title: how to convert object type to datetime64[ns] in python jupyter?
body: <p>I have a column of object type like this:</p>
  
  <pre><code> quote['SellTime'].head()
  
  
   Out[32]:
    0    94520
    1    94538
    2    94609
    3    94615    
    4    94617
    Name: SellTime, dtype: object
  </code></pre>
  
  <p>I want to convert it to  to date time (datetime64[ns]) format.</p>
  
  <p>I have done the following code:</p>
  
  <pre><code> quote['SellTime'].astype(str).astype(int)
   t2 = quote['SellTime'].astype(str).str.zfill(6)
   quote['SellTime'] = pd.to_datetime(t2, format='%H%M%S').dt.time
  </code></pre>
  
  <p>But it is still object type:</p>
  
  <pre><code> quote['SellTime'].head()
  
   0    09:45:20
   1    09:45:38
   2    09:46:09
   3    09:46:15
   4    09:46:17
   Name: SellTime, dtype: object
  </code></pre>