title: excluding specific rows in pandas dataframe
body: <p>I am trying to create a new dataframe selecting only those rows which a specific column value does not start with a capital S.
  I have tried the following options:</p>
  <pre><code>New_dataframe = dataframe.loc[~dataframe.column.str.startswith(('S'))]
  
  filter = dataframe['column'].astype(str).str.contains(r'^\S')
  New_dataframe  = dataframe[~filter]
  </code></pre>
  <p>However both options return an empty dataframe. Does anybody have a better solution?</p>