How to automagically assign weight to a Zend Tag Cloud?

In the Zend Framework is a very nice and easy way to create a开发者_如何学运维 Tag cloud, but the documentation gives no clue about a way to automagically give every tag a weight. Is there a way to do this? If no, how could it best be done?

The Zend Tag Cloud code example seems to indicate that weight is set the tag array