title: Pick lines with highest values from np.zeros
body: <p>I have the following data structure:</p>
  
  <pre><code>Pl = np.zeros((7,2,7))
  Pl[0,0,1]=1
  Pl[1,0,2]=1
  Pl[2,0,3]=1
  Pl[5,0,6]=0.9
  Pl[5,0,5]=0.1
  ...
  Pl[5,1,4]=1
  </code></pre>
  
  <p>How can I get the entry with a specified first value and that has the highest assigned value? </p>
  
  <p>For example for x=5, I want to get Pl[5,1,4]. I have seen max but I can't specify the value of x.</p>
  
  <p>Thank you!</p>