title: PHP Array_Sum on multi dimensional array
body: <p>If I have a multi dimensional array in PHP like so...</p>
  
  <pre><code>    [0] =&gt; Array
      (
          [url] =&gt; http://domain1.com
          [domain] =&gt; domain1.com
          [values] =&gt; Array
              (
                  [character_length] =&gt; 25
                  [word_count] =&gt; 7
              )
  
      )
  
      [1] =&gt; Array
      (
          [url] =&gt; http://domain2.com
          [domain] =&gt; domain2.com
          [values] =&gt; Array
              (
                  [character_length] =&gt; 30
                  [word_count] =&gt; 7
  
      )
  </code></pre>
  
  <p>How can I merge them to produce....</p>
  
  <pre><code>    [0] =&gt; Array
      (
          [url] =&gt; *can be anything*
          [domain] =&gt; *can be anything*
          [values] =&gt; Array
              (
                  [character_length] =&gt; 55
                  [word_count] =&gt; 14
              )
  
      )
  </code></pre>