reduce.js

App.CompanyItemController = Ember.ObjectController.extend({
  total: Ember.reduceComputed("deals.@each.{status,value}", {
    initialValue: 0,
    addedItem: function(accumulatedValue, item, changeMeta, instanceMeta) {
      if (item.get('state') === 'lost') {
        return accumulatedValue;
      }
      return accumulatedValue + item.get('value');
    },
    removedItem: function(accumulatedValue, item, changeMeta, instanceMeta) {
      if (item.get('state') === 'lost') {
        return accumulatedValue;
      }
      return accumulatedValue - item.get('value');
    }
  }),
  dealTotals: App.computed.groupable('deals',function(deal){
     return deal.get('state'); 
  })
});