private double GetRating(UserArticleRatings user, List <UserArticleRatings> neighbors, int articleId)
{
int articleIndex = ratings.ArticleIndexToID.IndexOf(articleId);
var nonZero = user.ArticleRatings.Where(x => x != 0);
double avgUserRating = nonZero.Count() > 0 ? nonZero.Average() : 0.0;
double score = 0.0;
int count = 0;
for (int u = 0; u < neighbors.Count; u++)
{
var nonZeroRatings = neighbors[u].ArticleRatings.Where(x => x != 0);
double avgRating = nonZeroRatings.Count() > 0 ? nonZeroRatings.Average() : 0.0;
if (neighbors[u].ArticleRatings[articleIndex] != 0)
{
score += neighbors[u].ArticleRatings[articleIndex] - avgRating;
count++;
}
}
if (count > 0)
{
score /= count;
score += avgUserRating;
}
return(score);
}
public double GetRating(int userId, int articleId)
{
UserArticleRatings user = ratings.Users.FirstOrDefault(x => x.UserID == userId);
List <UserArticleRatings> neighbors = GetNearestNeighbors(user, neighborCount);
return(GetRating(user, neighbors, articleId));
}
public List <Suggestion> GetSuggestions(int userId, int numSuggestions)
{
int userIndex = ratings.UserIndexToID.IndexOf(userId);
UserArticleRatings user = ratings.Users[userIndex];
var art1 = ratings.art.OrderBy(m => m.ArticleID).ToList();
var user1 = ratings.Users.OrderBy(m => m.UserID).ToList();
List <Suggestion> suggestions = new List <Suggestion>();
var neighbors = GetNearestNeighbors(user, neighborCount);
for (int articleIndex = 0; articleIndex < ratings.ArticleIndexToID.Count; articleIndex++)
{
// If the user in question hasn't rated the given article yet
if (user.ArticleRatings[articleIndex] == 0)
{
double score = 0.0;
int count = 0;
for (int u = 0; u < neighbors.Count; u++)
{
if (neighbors[u].ArticleRatings[articleIndex] != 0)
{
// Calculate the weighted score for this article
score += neighbors[u].ArticleRatings[articleIndex] - ((u + 1.0) / 100.0);
count++;
}
}
if (count > 0)
{
score /= count;
}
suggestions.Add(new Suggestion(userId, art1[articleIndex].ArticleID, art1[articleIndex].ArticleName, score));
// suggestions.Add(new Suggestion(userId, ratings.ArticleIndexToID[articleIndex],ratings.Ang1[articleIndex], score));
}
}
suggestions.Sort((c, n) => n.Rating.CompareTo(c.Rating));
return(suggestions.Take(numSuggestions).ToList());
}
private List <UserArticleRatings> GetNearestNeighbors(UserArticleRatings user, int numUsers)
{
List <UserArticleRatings> neighbors = new List <UserArticleRatings>();
for (int i = 0; i < ratings.Users.Count; i++)
{
if (ratings.Users[i].UserID == user.UserID)
{
ratings.Users[i].Score = double.NegativeInfinity;
}
else
{
ratings.Users[i].Score = comparer.CompareVectors(ratings.Users[i].ArticleRatings, user.ArticleRatings);
}
}
var similarUsers = ratings.Users.OrderByDescending(x => x.Score);
return(similarUsers.Take(numUsers).ToList());
}
public void Load(string file)
{
ratings = new UserArticleRatingsTable();
using (FileStream fs = new FileStream(file, FileMode.Open))
using (GZipStream zip = new GZipStream(fs, CompressionMode.Decompress))
using (StreamReader r = new StreamReader(zip))
{
long total = long.Parse(r.ReadLine());
int features = int.Parse(r.ReadLine());
for (long i = 0; i < total; i++)
{
int userId = int.Parse(r.ReadLine());
UserArticleRatings uat = new UserArticleRatings(userId, features);
for (int x = 0; x < features; x++)
{
uat.ArticleRatings[x] = double.Parse(r.ReadLine());
}
ratings.Users.Add(uat);
}
total = int.Parse(r.ReadLine());
for (int i = 0; i < total; i++)
{
ratings.UserIndexToID.Add(int.Parse(r.ReadLine()));
}
total = int.Parse(r.ReadLine());
for (int i = 0; i < total; i++)
{
ratings.ArticleIndexToID.Add(int.Parse(r.ReadLine()));
}
}
FillTransposedRatings();
}
public List <Suggestion> GetSuggestions(int userId, int numSuggestions)
{
int userIndex = ratings.UserIndexToID.IndexOf(userId);
UserArticleRatings user = ratings.Users[userIndex];
List <Suggestion> suggestions = new List <Suggestion>();
for (int articleIndex = 0; articleIndex < ratings.ArticleIndexToID.Count; articleIndex++)
{
// If the user in question hasn't rated the given article yet
if (user.ArticleRatings[articleIndex] == 0)
{
double rating = GetRatingForIndex(userIndex, articleIndex);
suggestions.Add(new Suggestion(userId, ratings.ArticleIndexToID[articleIndex], rating));
}
}
suggestions.Sort((c, n) => n.Rating.CompareTo(c.Rating));
return(suggestions.Take(numSuggestions).ToList());
}
public void Load(string file)
{
ratings = new UserArticleRatingsTable();
using (FileStream fs = new FileStream(file, FileMode.Open))
using (GZipStream zip = new GZipStream(fs, CompressionMode.Decompress))
using (StreamReader r = new StreamReader(zip))
{
numUsers = int.Parse(r.ReadLine());
numArticles = int.Parse(r.ReadLine());
numFeatures = int.Parse(r.ReadLine());
double averageGlobalRating = double.Parse(r.ReadLine());
double[] userBiases = new double[numUsers];
for (int userIndex = 0; userIndex < numUsers; userIndex++)
{
userBiases[userIndex] = double.Parse(r.ReadLine());
}
double[] articleBiases = new double[numArticles];
for (int articleIndex = 0; articleIndex < numArticles; articleIndex++)
{
articleBiases[articleIndex] = double.Parse(r.ReadLine());
}
double[][] userFeatures = new double[numUsers][];
for (int userIndex = 0; userIndex < numUsers; userIndex++)
{
userFeatures[userIndex] = new double[numFeatures];
for (int featureIndex = 0; featureIndex < numFeatures; featureIndex++)
{
userFeatures[userIndex][featureIndex] = double.Parse(r.ReadLine());
}
}
double[][] articleFeatures = new double[numArticles][];
for (int articleIndex = 0; articleIndex < numUsers; articleIndex++)
{
articleFeatures[articleIndex] = new double[numFeatures];
for (int featureIndex = 0; featureIndex < numFeatures; featureIndex++)
{
articleFeatures[articleIndex][featureIndex] = double.Parse(r.ReadLine());
}
}
svd = new SvdResult(averageGlobalRating, userBiases, articleBiases, userFeatures, articleFeatures);
for (int i = 0; i < numUsers; i++)
{
int userId = int.Parse(r.ReadLine());
UserArticleRatings uat = new UserArticleRatings(userId, numArticles);
for (int x = 0; x < numArticles; x++)
{
uat.ArticleRatings[x] = double.Parse(r.ReadLine());
}
ratings.Users.Add(uat);
}
for (int i = 0; i < numUsers; i++)
{
ratings.UserIndexToID.Add(int.Parse(r.ReadLine()));
}
for (int i = 0; i < numArticles; i++)
{
ratings.ArticleIndexToID.Add(int.Parse(r.ReadLine()));
}
}
}
