title: Intersection of 2-d numpy arrays
body: <p>I am looking for a way to get the intersection between two 2-dimensional <code>numpy.array</code> of shape <code>(n_1, m)</code> and <code>(n_2, m)</code>. Note that <code>n_1</code> and <code>n_2</code> can differ but m is the same for both arrays. Here are two minimal examples with the expected results:</p>
  
  <pre><code>import numpy as np
  
  array1a = np.array([[2], [2], [5], [1]])
  array1b = np.array([[5], [2]])
  
  array_intersect(array1a, array1b)
  ##  array([[2],
  ##         [5]])
  
  
  array2a = np.array([[1, 2], [3, 3], [2, 1], [1, 3], [2, 1]])
  array2b = np.array([[2, 1], [1, 4], [3, 3]])
  
  array_intersect(array2a, array2b)
  ##  array([[2, 1],
  ##         [3, 3]])
  </code></pre>
  
  <p>If someone have a clue on how I should implement the <code>array_intersect</code> function, I would be very grateful!</p>