private static ScoreClass GetLowestNeighbour(List <ScoreClass> list)
{
ScoreClass res = null;
foreach (var x in list)
{
if (res != null)
{
if (x.Score < res.Score)
{
res = x;
}
else if (x.Score == res.Score)
{
if (x.ExtraArticles < res.ExtraArticles || x.SameArticles < res.SameArticles)
{
res = x;
}
}
}
else
{
res = x;
}
}
return(res);
}
public List <ScoreClass> Find(Dictionary <int, UserPreferences> dataSet, int targetUser, double minThreshold, IMeasureSimularity type, int neighbourAmount)
{
var neighbours = new List <ScoreClass>();
var client = new MeasureClient(type);
ScoreClass lowestNeighbour = null;
var targetUserPrefKeys = dataSet[targetUser].Prefs.Keys.ToList();
//Loop through dataset of UserPreferences classes
foreach (var pair in dataSet)
{
if (pair.Key != targetUser)
{
var scorevalue = client.Measure(dataSet[targetUser], pair.Value);
var uPrefsKeys = pair.Value.Prefs.Keys.ToList();
// ScoreClass is a simple class that stores a score with an user id
var score = new ScoreClass
{
User = pair.Value,
Score = scorevalue,
ExtraArticles = uPrefsKeys.Except(targetUserPrefKeys).ToList().Count,
SameArticles = uPrefsKeys.Intersect(targetUserPrefKeys).ToList().Count
};
// Score has to be larger than treshHold AND have additional articles relative to the target user
if (score.Score >= minThreshold && score.ExtraArticles > 0 && score.SameArticles > 2)
{
// neighbours list isn't full yet, add the score.
if (neighbours.Count() < neighbourAmount)
{
if (lowestNeighbour == null || score.Score < lowestNeighbour.Score)
{
lowestNeighbour = score;
}
neighbours.Add(score);
}
// else if score is higher than lowestNeighbour score
else if (score.Score > lowestNeighbour.Score)
{
var index = neighbours.IndexOf(lowestNeighbour);
if (index == -1)
{
break;
}
neighbours.RemoveAt(index);
neighbours.Add(score);
lowestNeighbour = GetLowestNeighbour(neighbours);
}
// else if score == lowestneighbour and score has more "value" (more new articles)
else if (score.ExtraArticles > lowestNeighbour.ExtraArticles && score.Score == lowestNeighbour.Score)
{
var index = neighbours.IndexOf(lowestNeighbour);
if (index == -1)
{
break;
}
neighbours.RemoveAt(index);
neighbours.Add(score);
lowestNeighbour = GetLowestNeighbour(neighbours);
}
//Console.WriteLine("User " + targetUser + " scores " + score.Score.ToString("0.000") + " with user " + pair.Key + " and has " + score.ExtraArticles + " extra values");
}
//else { Console.WriteLine("Score was too low to be considered, or user didn't have added value)"); }
}
}
var sortedNeighbours = neighbours.OrderByDescending(s => s.Score).ToList();
return(sortedNeighbours);
}
