title: calculating percentage error by comparing two arrays
body: <p>I have some data in two numpy arrays.</p>
  
  <pre><code>a = [1, 2, 3, 4, 5, 6, 7]
  b = [1, 2, 3, 5, 5, 6, 7]
  </code></pre>
  
  <p>I say array <code>a</code> is my calculated result and array <code>b</code> are the true result values. I want to calculate the error percentage in my result.
  Now I can loop through the two arrays and compare them <code>0</code> if the values match and <code>1</code> for a mismatch then add them up, divide by the total values and calculate percentage error. </p>
  
  <p>Is there any possible faster and elegant method for doing this ? </p>