title: Iterate and modify array with NumPy
body: <p>I have two vectors <code>x</code> and <code>y</code> with same length defined with NumPy.</p>
  
  <p>How can I iterate through <code>x</code> and modify values in <code>y</code>?</p>
  
  <p>I mean something like</p>
  
  <pre><code>ingredients = empty(cakes.shape)
  for ingredient, cake in np.nditer([ingredients,cakes]):
      ingredient = cake * 2 + 2
  </code></pre>