title: Convert to datetime, but how to drop '1900-01-01' in python
body: <p>I have a time series only contains hours, minutes, and seconds, when I use datetime convert it into datetime type, it added '1900-01-01' as a date automatically. How to drop the date? I would like to get a datetime type data for further matplotlib plotting.</p>
  <p>My code is</p>
  <pre><code>df['Time(H:M:S)']=pd.to_datetime(df['Time(H:M:S)'], format='%H:%M:%S')
  </code></pre>