title: Aggregate dataframe based on 2 categorical columns and value of 1 python
body: <p>with the following sample:</p>
  
  <pre><code>Offer Client amount
  
  'Off1' 'C1'  1000
  'Off1' 'C1'  10
  'Off1' 'C2'  2222
  'Off1' 'C3'  0
  'Off1' 'C3'  10
  'Off2' 'C4'  11
  'Off2' 'C1'  2342
  'Off3' 'C3'  2131
  'Off3' 'C100' 121
  'Off3' 'C1'   1231
  'Off3' 'C1'   31
  </code></pre>
  
  <p>I would like to aggregate the data based on each offer and client in order to 
  get the max amount.</p>
  
  <p>The result would be:</p>
  
  <pre><code>Offer Client amount 
  
  'Off1' 'C1'  1000
  'Off1' 'C2'  2222
  'Off1' 'C3'  10
  'Off2' 'C4'  11
  'Off2' 'C1'  2342
  'Off3' 'C3'  2131
  'Off3' 'C100' 121
  'Off3' 'C1'   1231
  </code></pre>
  
  <ul>
  <li><p>In each offer, a candidate can have several amount of money, so the target is keeping the max value of each candidate in each offer.</p></li>
  <li><p>In the case we would like to keep the minimun and maximun offer of each candidate.</p></li>
  </ul>