title: Time difference between two columns in Pandas
body: <p>How can I subtract the time between two columns and convert it to minutes </p>
  
  <pre><code>         Date Time Ordered Time Delivered
  0  1/11/19   9:25:00 am    10:58:00 am
  1  1/11/19  10:16:00 am    11:13:00 am
  2  1/11/19  10:25:00 am    10:45:00 am
  3  1/11/19  10:45:00 am    11:12:00 am
  4  1/11/19  11:11:00 am    11:47:00 am
  </code></pre>
  
  <p>I want to subtract the Time_delivered - Time_ordered to get the minutes the delivery took.</p>
  
  <pre><code>df.time_ordered = pd.to_datetime(df.time_ordered)
  
  </code></pre>
  
  <p>This doesn't output the correct time instead it adds today's date the time</p>