title: len() of a numpy array in python
body: <p>If I use <code>len(np.array([[2,3,1,0], [2,3,1,0], [3,2,1,1]]))</code>, I get back 3.  </p>
  
  <p>Why is there no argument for <code>len()</code> about which axis I want the length of in multidimensional arrays? This is alarming.  Is there an alternative?</p>