title: Why does zip change my lists?
body: <p>I noticed a (to me) very strange behavior, I don't understand:
  I got a list and an numpy array both with binary values and I want to check the true positives (both==1 at the same time).</p>
  
  <pre><code>import numpy as np
  a = [0,0,1,1]
  b = np.array([1,0,1,0])
  
  for a,b in zip(a,b):
    if a==1 and b==1:
        print "cool"
  print a,b
  </code></pre>
  
  <p>Now the craziness begins. a and b are not longer a list or a numpy array but an integer and numpy float? How on earth did that happen?
  Thanks for your help!</p>