title: Datetime Conversion with ValueError
body: <p>I have a pandas dataframe with columns containing start and stop times in this format: <code>2016-01-01 00:00:00</code></p>
  
  <p>I would like to convert these times to datetime objects so that I can subtract one from the other to compute total duration. I'm using the following:</p>
  
  <pre><code>import datetime
  
  df = df['start_time'] = 
  df['start_time'].apply(lambda x:datetime.datetime.strptime(x,'%Y/%m/%d/%T %I:%M:%S %p'))
  </code></pre>
  
  <p>However, I have the following ValueError:</p>
  
  <p><code>ValueError: 'T' is a bad directive in format '%Y/%m/%d/%T %I:%M:%S %p'</code></p>