title: calculating sum in objects
body: <p>I am in need to do this thing:
  I have an object like below, but i am in need to do the sum of the numbers of objects like  object1_(anything), object2_(anything)</p>
  
  <pre><code>stdClass Object
  (
      [object1_2012_06_12] =&gt; 16
      [object2_2012_06_12] =&gt; 10
      [object1_2012_06_11] =&gt; 16
      [object2_2012_06_11] =&gt; 10
  )
  </code></pre>
  
  <p>For examaple: sum of <strong>object1_(<em>anything</em>)</strong> will be (object1_2012_06_12 + object1_2012_06_11) = (16+16)=32</p>