title: Dynamically populate an associative array in PHP
body: <p>I have an array with the following 6 strings.</p>
  
  <pre><code>user1 A
  user2 B
  user4 C
  user2 D
  user1 E
  </code></pre>
  
  <p>I need to create a Dictionary like:</p>
  
  <pre><code>arr['user1'] =&gt; ['A', 'E']
  arr['user2'] =&gt; ['B', 'D']
  arr['user4'] =&gt; ['C']
  </code></pre>
  
  <p>How to do this in PHP?</p>