title: Find 1D array from 2D NumPy arrays?
body: <p>Suppose I have </p>
  
  <pre><code>[[array([x1, y1]), z1]
   [array([x2, y1]), z2]
   ......
   [array([xn, yn]), zn]
  ]
  </code></pre>
  
  <p>And I want to find the index of <code>array([x5, y5])</code>. How can find effieciently using NumPy?</p>