title: How to get indices of np.amin of 3d np array?
body: <p>Given the following code:</p>
  <pre><code>import numpy as np
  
  x = np.array([[[1, 2],
                 [3, 4]],
                
                [[5, 6],
                 [7, 8]], 
                
                [[3, 1],
                 [1, 5]]])
  
  x_min = np.amin(x, axis=0)
  print(x_min)
  </code></pre>
  <p>The output (x_min) is</p>
  <pre><code>[[1 1]
   [1 4]]
  </code></pre>
  <p>Now I want to get the indices of dimension 0 of array x for the results of x_min array, it should be:</p>
  <pre><code>[[0 2]
   [2 0]]
  </code></pre>
  <p>Which function can I use to get this indices?</p>