title: Find ordered vector in numpy array
body: <p>I need to find a vector in a numpy.array. 
  For example, I have a np.array named e and I want to find the vector [1, 2] in e (meaning that I would like to have the index of the vector inside the matrix) but apparently my programm see the vector even when is not present:</p>
  
  <p><img src="https://i.stack.imgur.com/MauHe.png" alt="enter image description here"> </p>
  
  <p>The code I use to built e in the following: </p>
  
  <pre><code>import numpy as np
  faces = np.array([[1,2,3,4],[5,6,2,1],[6,7,3,2],[7,8,4,3],[8,5,1,4],[8,7,6,5]])
  e = np.zeros([6,4,2])
  for k in range(len(faces)):
      a = [faces[k][0], faces[k][1]]
      b = [faces[k][1], faces[k][2]] 
      c = [faces[k][2], faces[k][3]]
      d = [faces[k][3], faces[k][0]]
      e[k] = np.array([a,b,c,d])
   print('e: %s' %e)
  </code></pre>
  
  <p>any clue how to solve this? </p>