title: renaming column in dataframe for Pandas using regular expression
body: <p>I have a dataframe made by Pandas that I want to remove the empty space at the end of each column name. I tried something like:</p>
  
  <pre><code>raw_data.columns.values = re.sub(' $','',raw_data.columns.values)
  </code></pre>
  
  <p>But this is not working, anything I did wrong here?</p>