title: Removing the timestamp from a datetime in pandas dataframe
body: <p><strong>Scenario:</strong> I have a dataframe with multiple columns retrieved from excel worksheets. Some of these columns are dates: some have just the date (yyyy:mm:dd) and some have date and timestamp (yyyy:mm:dd 00.00.000000).</p>
  
  <p><strong>Question:</strong> How can I remove the time stamp from the dates when they are not the index of my dataframe?</p>
  
  <p><strong>What I already tried:</strong> From other posts here in SO (<a href="https://stackoverflow.com/questions/25653220/working-with-dates-in-pandas-remove-unseen-characters-in-datetime-and-convert">working with dates in pandas - remove unseen characters in datetime and convert to string</a> and <a href="https://stackoverflow.com/questions/41954938/how-to-strip-a-pandas-datetime-of-date-hours-and-seconds">How to strip a pandas datetime of date, hours and seconds</a>) I found:</p>
  
  <pre><code>pd.DatetimeIndex(dfST['timestamp']).date
  </code></pre>
  
  <p>and</p>
  
  <pre><code>strfitme (df['timestamp'].apply(lambda x: x.strftime('%Y-%m-%d'))
  </code></pre>
  
  <p>But I can't seem to find a way to use those directly to the wanted column when it is not the index of my dataframe.</p>