Simple example of parsing Yelps category structure to dereference an ID

find_category.php

<?

function find_category($id, $categories){
	if(!count($categories)) return false;
	foreach($categories as $set){
		if($set['id'] == $id) return $set['t'];
		$category = find_category($id, $set['c']);
		if($category) break;
	}
	
	return $category;
}

$category = find_category('-Z6XiTi5GStH07pq0NmlZg', json_decode(file_get_contents('http://www.yelp.com/category_tree_json'), true));

?>