title: Listing unique data from liquid objects
body: <p>I need to be able take a list of objects in liquid and display them on the page in a specific format.</p>
  
  <p>If I have an array of objects (pages), I need to be able to print them in the following way:</p>
  
  <p>list category names (page.category.name)</p>
  
  <p>list each subcategory name with a list of pages under each subcategory name (page.subcategory.name and page.title)</p>
  
  <p>Typically in ruby I would simply group the pages but I can't do that in liquid. The other thing I tried was to capture unique lists of categories and subcategories for pages but I couldn't find a way to get a unique list of items from an array. Any suggest help would be great.</p>