title: Python : find difference between two arrays in python
body: <p>I have two arrays in python.</p>
  
  <pre><code>arr1 = [(7, 0.78, 7920), (8, 0.9, 9000)]
  arr2 = [(7, 1.68, 8460)]
  </code></pre>
  
  <p>In this array first value is <code>ID</code> (7,8,7).I want result basis on <code>ID</code>. If ID same then get difference between others two value.<br/>
  Between <code>arr1</code> and <code>arr2</code> ID 7 is same then will be subtraction (1.68-0.78 = 0.9) And (8460-7920 = 540) otherwise it will be same.
  How to get Result like that ?</p>
  
  <pre><code>diffArray = [(7, 0.9, 540), (8, 0.9, 9000)]
  </code></pre>