title: Python/Pandas convert string to time only
body: <p>I have the following Pandas dataframe in Python 2.7.</p>
  
  <pre><code>import pandas as pd
  trial_num = [1,2,3,4,5]
  sail_rem_time = ['11:33:11','16:29:05','09:37:56','21:43:31','17:42:06']
  dfc = pd.DataFrame(zip(*[trial_num,sail_rem_time]),columns=['Temp_Reading','Time_of_Sail'])
  print dfc
  </code></pre>
  
  <p>The dataframe looks like this:</p>
  
  <pre><code>  Temp_Reading Time_of_Sail
               1     11:33:11
               2     16:29:05
               3     09:37:56
               4     21:43:31
               5     17:42:06
  </code></pre>
  
  <p>This dataframe comes from a *.csv file. I use Pandas to read in the *.csv file as a Pandas dataframe. When I use <code>print dfc.dtypes</code>, it shows me that the column <code>Time_of_Sail</code> has a datatype <code>object</code>. I would like to convert this column to <code>datetime</code> datatype BUT I only want the time part - I don't want the year, month, date.</p>
  
  <p>I can try this:</p>
  
  <pre><code>dfc['Time_of_Sail'] = pd.to_datetime(dfc['Time_of_Sail'])
  dfc['Time_of_Sail'] = [time.time() for time in dfc['Time_of_Sail']]
  </code></pre>
  
  <p>but the problem is that the when I run <code>print dfc.dtypes</code> it still shows that the column <code>Time_of_Sail</code> is <code>object</code>.</p>
  
  <p>Is there a way to convert this column into a datetime format that only has the time?</p>
  
  <p><strong>Additional Information:</strong></p>
  
  <p>To create the above dataframe and output, this also works:</p>
  
  <pre><code>import pandas as pd
  trial_num = [1,2,3,4,5]
  sail_rem_time = ['11:33:11','16:29:05','09:37:56','21:43:31','17:42:06']
  data = [
      [trial_num[0],sail_rem_time[0]],
      [trial_num[1],sail_rem_time[1]],[trial_num[2],sail_rem_time[2]],
      [trial_num[3],sail_rem_time[3]]
      ]
  dfc = pd.DataFrame(data,columns=['Temp_Reading','Time_of_Sail'])
  dfc['Time_of_Sail'] = pd.to_datetime(dfc['Time_of_Sail'])
  dfc['Time_of_Sail'] = [time.time() for time in dfc['Time_of_Sail']]
  print dfc
  print dfc.dtypes
  </code></pre>