title: How to remove the date information in a column, just keep time
body: <p>I am using pandas dataframe. there is a specific column has time information.</p>
  
  <p>the raw data likes this:</p>
  
  <pre><code>5:15am
  5:28am
  6:15am
  </code></pre>
  
  <p>so I need to convert the raw data into datetime format:</p>
  
  <pre><code>format = '%I:%M%p'
  dataset['TimeStamp'] = pd.to_datetime(dataset['TimeStamp'],format)
  </code></pre>
  
  <p>However, I got:</p>
  
  <pre><code>2014-07-04 05:15:00
  2014-07-04 05:28:00
  2014-07-04 06:15:00
  </code></pre>
  
  <p>I don't want the year and date information, just want time. How can I remove it. Thanks.</p>