title: Get consecutive ratios of elements python
body: <p>Is there a simple way to get the ratios of consecutive elements of a numpy array?</p>
  
  <p>Basically something similar to numpy.diff(x)?</p>
  
  <p>so if x=[1,2,10,100 ...] </p>
  
  <p>I would like [0.5 ,0.2, 0.1 ...] 
  ie [x1/x2, x2/x3 , x3/x4]  </p>
  
  <p>I know I can do this easily by shifting and dividing, but it seems clumsy compared to numpy.diff(x)</p>