title: Shift all indices in NumPy array
body: <p>I have a numpy array like this:  </p>
  
  <pre><code>x=np.array([0,1,2,3,4])
  </code></pre>
  
  <p>and want to create an array where the value in index 0 is in index 1, index 1 is in index 2, etc.</p>
  
  <p>The output I want is:</p>
  
  <pre><code>y=np.array([0,0,1,2,3]).
  </code></pre>
  
  <p>I'm guessing there's an easy way to do this without iterating through the full array. How can I do this in a numPythonic way?</p>