public Dictionary <double, double> PredictAllRatings(PredictionMethod m, string sUID, string sIID)
{
SimilartyData <string> similarityData = null;
switch (m)
{
case PredictionMethod.Pearson:
similarityData = usr2usr[m];
break;
case PredictionMethod.Cosine:
similarityData = usr2usr[m];
break;
case PredictionMethod.Random:
break;
case PredictionMethod.SVD:
break;
case PredictionMethod.Stereotypes:
break;
default:
break;
}
if (similarityData == null)
{
throw new NotImplementedException();
}
IEnumerable <string> users = getUsers(sUID, sIID, similarityData).ToList();
Dictionary <double, double> rankToSumSimilarity = new Dictionary <double, double>();
foreach (var usr in users)
{
var rank = _db.GetRank(usr, sIID);
if (!rankToSumSimilarity.ContainsKey(rank.Value))
{
rankToSumSimilarity[rank.Value] = 0;
}
double sim = similarityData.GetSimilarity(sUID, usr);
if (sim > 0)
{
rankToSumSimilarity[rank.Value] += sim;
}
}
return(rankToSumSimilarity);
}
private IEnumerable <string> getUsers(string sUID, string sIID, SimilartyData <string> similarityData)
{
IEnumerable <string> users;
if (Mode == FilterMode.MaxUsers)
{
users = _db.GetRankersOfItem(sIID).Where(usr => usr != sUID).OrderByDescending(usr => similarityData.GetSimilarity(sUID, usr)).Take(MaxUsers);
}
else
{
users = _db.GetRankersOfItem(sIID).
Where(usr => usr != sUID &&
similarityData.GetSimilarity(sUID, usr) >= MinSimilarity).ToList();
}
return(users);
}
public double PredictRating(PredictionMethod m, string sUID, string sIID)
{
SimilartyData similarityData = null;
switch (m)
{
case PredictionMethod.Pearson:
similarityData = usr2usr[m];
break;
case PredictionMethod.Cosine:
similarityData = usr2usr[m];
break;
case PredictionMethod.Random:
return(GetRandomRank(sUID));
case PredictionMethod.SVD:
return(_svd.Predict(sUID, sIID));
case PredictionMethod.Stereotypes:
break;
default:
break;
}
if (similarityData == null)
{
throw new NotImplementedException();
}
IEnumerable <string> users = getUsers(sUID, sIID, similarityData).ToList();
double mone = 0;
foreach (var usr in users)
{
if (usr == sUID)
{
continue;
}
double avg = _db.GetRanks(usr).Average();
var sim = similarityData.GetSimilarity(sUID, usr);
if (sim > 0)
{
mone += sim * (_db.GetRank(usr, sIID).Value - avg);
}
}
double avgCurrent = 0;
var ranks = _db.GetRanks(sUID).ToList();
if (ranks.Count > 0)
{
avgCurrent = ranks.Average();
}
if (mone == 0)
{
return(avgCurrent);
}
double mechane = 0;
foreach (var usr in users)
{
if (usr == sUID)
{
continue;
}
var sim = similarityData.GetSimilarity(sUID, usr);
if (sim > 0)
{
mechane += sim;
}
}
//mechne will be zero only if mone will be zero, and if move is zero
//we already exit
return(avgCurrent + mone / mechane);
}