title: Tricky numpy argmax on last dimension of 3-dimensional ndarray
body: <p>if have an array of shape (9,1,3).</p>
  
  <pre><code>array([[[  6,  12, 108]],
  
     [[122, 112,  38]],
  
     [[ 57, 101,  62]],
  
     [[119,  76, 177]],
  
     [[ 46,  62,   2]],
  
     [[127,  61, 155]],
  
     [[  5,   6, 151]],
  
     [[  5,   8, 185]],
  
     [[109, 167,  33]]])
  </code></pre>
  
  <p>I want to find the argmax index of the third dimension, in this case it would be 185, so index 7.</p>
  
  <p>I guess the solution is linked to reshaping but I can't wrap my head around it. Thanks for any help!</p>