title: How to find max value in a numpy array column?
body: <p>I can find quite a few permutations of this question, but not this (rather simple) one: how do I find the maximum value of a specific column of a numpy array (in the most pythonic way)?</p>
  
  <pre><code>a = array([[10, 2], [3, 4], [5, 6]])
  </code></pre>
  
  <p>What I want is the max value in the first column and second column (these are x,y coordinates and I eventually need the height and width of each shape), so max x coordinate is 10 and max y coordinate is 6.</p>
  
  <p>I've tried:</p>
  
  <pre><code>xmax = numpy.amax(a,axis=0)
  ymax = numpy.amax(a,axis=1)
  </code></pre>
  
  <p>but these yield</p>
  
  <pre><code>array([10, 6])
  array([10, 4, 6])
  </code></pre>
  
  <p>...not what I expected.</p>
  
  <p>My solution is to use slices:</p>
  
  <pre><code>xmax = numpy.max(a[:,0])
  ymax = numpy.max(a[:,1])
  </code></pre>
  
  <p>Which works but doesn't seem to the best approach.</p>
  
  <p>Suggestions?</p>