title: Numpy Random Choice not working for 2-dimentional list
body: <p>I ran the following python code:</p>
  
  <pre><code>import numpy as np
  a_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 1, 2]]
  np.random.choice(a_list, size=20, 
      replace=True)
  </code></pre>
  
  <p>expecting a result like this:</p>
  
  <pre><code>[[7, 8, 9], [1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 1, 2], [1, 2, 3], [1, 2, 3], [10, 1, 2], [1, 2, 3], [7, 8, 9], [1, 2, 3], [1, 2, 3], [10, 1, 2], [4, 5, 6], [4, 5, 6], [10, 1, 2], [10, 1, 2], [7, 8, 9], [1, 2, 3], [7, 8, 9]]
  </code></pre>
  
  <p>but what I got instead was the error message below:</p>
  
  <pre><code> ValueError                           Traceback (most recent call last)
   &lt;ipython-input-80-c11957aca587&gt; in &lt;module&gt;()
      2 a_list = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 1, 2]]
      3 np.random.choice(a_list, size=20, 
  ----&gt; 4 replace=True)
  
  mtrand.pyx in mtrand.RandomState.choice()
  
  ValueError: a must be 1-dimensional
  </code></pre>
  
  <p>How do you randomly choose from a 2-dimensional list?</p>