title: Maximum of a list by an index
body: <p>My lists are :</p>
  
  <pre><code>ptotal: [13545.75, 13009.5, 13009.5, 13009.500000000002]
  
  backk1: [0, 11.5, 25.8, 39.0, 39.0, 39.0, 25.8, 11.5, 0, 11.5, 25.8, 39.0, 39.0, 0, 24.8, 24.7, 24.7, 24.7, 0, 24.7, 24.7, 24.7, 39.0, 39.0, 39.0]
  </code></pre>
  
  <p>I would like to find maximum value of list "ptotal" and its corresponding value in list "backk1". I have the following cod as a part of my whole program. It does not work well. Could you please help me?</p>
  
  <pre><code>ptotalfinal=max(ptotal) 
  
  ptotalindex= max(enumerate(ptotal),key=lambda x: x[1])[0]
  etaunk1max= (x in enumerate(zip(backetaunk1, ptotal),key=lambda x: x[1]))
  </code></pre>