public static RecommenderResult RecommendUser(
            this IMatrixFactorizationRecommender recommender,
            UserFeatures user)
        {
            if (recommender == null)
            {
                throw new ArgumentNullException(nameof(recommender));
            }

            if (user == null)
            {
                throw new ArgumentNullException(nameof(user));
            }

            return(recommender.RecommendUser(user, RecommenderResultBuilderFactory.Instance));
        }
        public static RecommenderResult RecommendUser(
            this IMatrixFactorizationRecommender recommender,
            IEnumerable <string> items)
        {
            if (recommender == null)
            {
                throw new ArgumentNullException(nameof(recommender));
            }

            if (items == null)
            {
                throw new ArgumentNullException(nameof(items));
            }

            return(recommender.RecommendUser(recommender.ComputeUserFactors(items)));
        }
        public static RecommenderResult RecommendUser(
            this IMatrixFactorizationRecommender recommender,
            Dictionary <string, double> items)
        {
            if (recommender == null)
            {
                throw new ArgumentNullException(nameof(recommender));
            }

            if (items == null)
            {
                throw new ArgumentNullException(nameof(items));
            }

            return(recommender.RecommendUser(recommender.ComputeUserFeatures(items)));
        }