public void ComputeDeviations8sec(Dictionary <int, UserPreferance> users)
{
int itemA; // x
int itemB; // y
// for each person in the data
foreach (KeyValuePair <int, UserPreferance> user in users)
{
Dictionary <int, double> ratings = user.Value.UserRatings;
// 2 for loop to loop through every ratings to get x and y
foreach (KeyValuePair <int, double> rating in ratings)
{
itemA = rating.Key;
// itemA doesnt exist yet in x
if (!data.ContainsKey(itemA))
{
data.Add(itemA, new Dictionary <int, DeviationData>());
}
foreach (KeyValuePair <int, double> rating2 in ratings)
{
itemB = rating2.Key;
if (itemA != itemB)
{
if (!data[itemA].ContainsKey(itemB))
{
data[itemA].Add(itemB, new DeviationData(0.0, 0));
}
data[itemA][itemB].nrOfPeople++;
data[itemA][itemB].deviationValue += rating.Value - rating2.Value;
}
}
}
}
// for each row
foreach (KeyValuePair <int, Dictionary <int, DeviationData> > pair in data)
{
//for each column
foreach (KeyValuePair <int, DeviationData> cell in pair.Value)
{
DeviationData data = cell.Value;
data.deviationValue /= data.nrOfPeople;
}
}
}
public double SlopeOneRecommendations(int target, Dictionary <int, double> ratings)
{
double numerator = 0.0;
int denominator = 0;
// for each item that user alrdy rated
foreach (KeyValuePair <int, double> rating in ratings)
{
// extract info about the dev between i(item rated by user) and the j
if (data[target].ContainsKey(rating.Key))
{
DeviationData deviationCell = data[target][rating.Key];
numerator += (rating.Value + deviationCell.deviationValue) * deviationCell.nrOfPeople;
denominator += deviationCell.nrOfPeople;
}
}
return(numerator / denominator);
}
public void Update(Dictionary <int, double> ratings, int article, double articleRating)
{
// update all articles connected to the ratings of the current user
foreach (KeyValuePair <int, double> rating in ratings)
{
// x
if (data.ContainsKey(article))
{
// y
if (data[article].ContainsKey(rating.Key))
{
DeviationData cell1 = data[article][rating.Key];
cell1.deviationValue = (cell1.deviationValue * cell1.nrOfPeople) + articleRating - rating.Value;
cell1.nrOfPeople++;
cell1.deviationValue /= cell1.nrOfPeople;
DeviationData cell2 = data[rating.Key][article];
cell2.deviationValue = -1 * cell1.deviationValue;
cell2.nrOfPeople = cell1.nrOfPeople;
}
}
}
ratings.Add(article, articleRating);
}
