public IEnumerable<KeyValuePair<int, double>> GetTopNItems(int userId,int n)
{
IPrediction userPrediction = new WeightedPrediction();
Dictionary<int, double> allItemPrediction = userPrediction.GetAllItemsPrediction(userId);
var topNItems = allItemPrediction
.OrderByDescending(s => s.Value)
.Take(n);
return topNItems;
}
