title: Split a datrafame pandas based on raw values interval in string format
body: <p>I have a little problem that I don't get solutions. I have this dataset as an example: Columns=[A,B,C]</p>
  <pre><code>A,B,C
  F,Relax,begin
  F,,
  F,,
  H,,
  H,,
  H,,
  G,,
  H,,
  I,,
  G,,
  H,Relax,end
  H,,
  H,,
  H,,
  F,,
  G,,
  A,,
  O,Cook,begin
  Q,,
  P,,
  I,,
  O,,
  R,,
  P,,
  O,Cook,end
  G,,
  H,,
  F,,
  G,,
  H,Relax,begin
  F,,
  G,,
  I,,
  I,,
  I,,
  I,,
  I,,
  I,,
  I,Relax,end
  H,,
  I,,
  G,,
  </code></pre>
  <p>I want to split this dataframe according to different intervals (<em>begin</em> and <em>end</em> in the C column) in many dataframes, and delete unnecessary raws (raws that are not present in intervals <em>begin</em> and <em>end</em>). For example, expected final dataframes:</p>
  <pre><code>dataframe 1
  A,B,C
  F,Relax,begin
  F,,
  F,,
  H,,
  H,,
  H,,
  G,,
  H,,
  I,,
  G,,
  H,Relax,end
  
  dataframe 2
  A,B,C
  O,Cook,begin
  Q,,
  P,,
  I,,
  O,,
  R,,
  P,,
  O,Cook,end
  
  dataframe 3
  A,B,C 
  H,Relax,begin
  F,,
  G,,
  I,,
  I,,
  I,,
  I,,
  I,,
  I,,
  I,Relax,end
  </code></pre>
  <p>Does everyone know how to solve this problem?
  Regards.</p>