title: max value from specified column in numpy array
body: <p>We need a maximum value from a numpy array with 3 columns.</p>
  
  <p>Sample, i need the maximum value per array of the last column.
  In this case the result is: 57.65048981 for the first array, 58.3501091 for the second and 56.86465836 for the third. How to get these 3 values in an array included by the 2 2 values in the columns before?</p>
  
  <pre><code>[array([[ 402.        ,  242.        ,   57.65048981],
     [ 401.        ,  243.        ,   56.32482529]]), 
  array([[ 356.        ,  257.        ,   53.3116188 ],
     [ 355.        ,  258.        ,   53.69690704],
     [ 356.        ,  258.        ,   57.52435684],
     [ 355.        ,  259.        ,   56.98838806],
     [ 356.        ,  259.        ,   57.81959152],
     [ 354.        ,  260.        ,   55.90369415],
     [ 355.        ,  260.        ,   58.14822769],
     [ 356.        ,  260.        ,   58.3501091 ],
     [ 354.        ,  261.        ,   55.1479187 ],
     [ 355.        ,  261.        ,   58.20180893],
     [ 354.        ,  262.        ,   54.5345459 ]]), 
  array([[ 386.        ,  260.        ,   56.86465836],
     [ 386.        ,  261.        ,   54.28659439],
     [ 386.        ,  259.        ,   56.53445435]])]
  </code></pre>
  
  <p>The result of this should be:</p>
  
  <pre><code>[[402, 242, 57.65048981],
  [356 ,260, 58.3501091],
  [386 ,260, 56.86465836]]
  </code></pre>