private double ComputeRMSE(PredictionMethod m, RecommenderSystemEngine engineTrain, IEnumerable <RankingDB.RankData> allTest)
{
double sum = 0;
foreach (var rankData in allTest)
{
double pretictedRating = Math.Round(engineTrain.PredictRating(m, rankData.ranker, rankData.item));
sum += Math.Pow((rankData.rank - pretictedRating), 2);
}
return(Math.Sqrt(sum / allTest.Count()));
}
//return an histogram of all ratings that the user has used
/*public Dictionary<double, int> GetRatingsHistogram(string sUID)
* {
* Dictionary<double, int> res = new Dictionary<double, int>();
*
* IEnumerable<double> AllRanks = _ratings.GetRanks(sUID);
* foreach (var rank in AllRanks)
* {
* if (!res.ContainsKey(rank))
* res[rank] = 0;
++res[rank];
* }
* return res;
* }*/
//predict the rating that a user will give to an item using one of the methods "Pearson", "Cosine", "Random"
public double PredictRating(PredictionMethod m, string sUID, string sIID)
{
return(_trainEngine.PredictRating(m, sUID, sIID));
}