private List <KeyValuePair <int, double> > PredictRatings(Matrix <int> ratingsMatrix, Matrix <float> weightsMatrix, RatingPredictor ratingPredictor, int user, int item)
{
List <KeyValuePair <int, double> > predictions = new List <KeyValuePair <int, double> >();
HashSet <int> randomItems = new HashSet <int>();
randomItems.Add(item);
Random random = new Random();
while (randomItems.Count < randomRatingsCount + 1)
{
int randomMovie = random.Next(this.moviesCount);
if (!ratingsMatrix[user].Contains(randomMovie))
{
randomItems.Add(randomMovie);
}
}
foreach (int i in randomItems)
{
double predictedRating = ratingPredictor.PredictRating(ratingsMatrix, weightsMatrix, user, i, false);
if (predictedRating > 0)
{
predictions.Add(new KeyValuePair <int, double>(i, predictedRating));
}
}
List <KeyValuePair <int, double> > orderedPredictions = predictions.OrderByDescending(x => x.Value).ToList();
return(orderedPredictions);
}