public double CalcPearson(UserP user, int minRatings = 0)
{
double sum1 = 0, sum2 = 0, sum1sq = 0, sum2sq = 0, psum = 0;
int n = 0;
// Iterate over all rating combinations
foreach (var rA in Ratings)
{
foreach (var rB in user.Ratings)
{
if (rA.MovieId == rB.MovieId &&
(rA.Movie.NumberOfRatings > minRatings || rB.Movie.NumberOfRatings > minRatings))
{
sum1 += rA.Score;
sum2 += rB.Score;
sum1sq += rA.Score * rA.Score;
sum2sq += rB.Score * rB.Score;
psum += rA.Score * rB.Score;
n++;
}
}
}
if (n == 0)
{
return(0);
}
double num = psum - ((sum1 * sum2) / n);
double den = Math.Sqrt((sum1sq - Math.Pow(sum1, 2.0) / n) * (sum2sq - Math.Pow(sum2, 2.0) / n));
return(num / den);
}
public UserViewModel(UserP u)
{
Id = u.Id;
Name = u.Name;
Distance = new DistanceMetric();
// RatingsP = u.Ratings;
}
public double CalcEuclidean(UserP user, int minRatings = 0)
{
double sim = 0;
int n = 0;
// Iterate over all rating combinations
foreach (var rA in Ratings)
{
foreach (var rB in user.Ratings)
{
if (rA.MovieId == rB.MovieId &&
(rA.Movie.NumberOfRatings > minRatings || rB.Movie.NumberOfRatings > minRatings))
{
sim += Math.Pow(rA.Score - rB.Score, 2.0);
n++;
}
}
}
// No ratings in common, return 0 else calculate inverted score
return(n == 0 ? 0 : 1 / (1 + sim));
}
public override bool Equals(Object obj)
{
UserP g = obj as UserP;
return(g != null && g.Id == this.Id);
}