title: PHP - shuffle only part of an array
body: <p>I have an array as so:</p>
  
  <pre><code>$animals = array (
      'giraffe',
      'lion',
      'hippo',
      'dog',
      'cat',
      'rabbit',
      'fly',
      'hamster',
      'gerbil'
      'goldfish'
  );
  </code></pre>
  
  <p>That is the order i want the array to be in apart from these 2 - <code>hamster</code> and <code>gerbil</code></p>
  
  <p>I would like to randomise between which one comes first. I know i can use:</p>
  
  <pre><code>shuffle($animals);
  </code></pre>
  
  <p>To randomise them all but i want to do it for just these 2. So if i was to do a <code>print_r($animals)</code> i may get hamster come before gerbil but another time get gerbil before hamster</p>