DynamicCentroidCluster.java

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package denoptim.fragmenter;
 
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
 
import org.apache.commons.math3.ml.distance.DistanceMeasure;
 
import denoptim.utils.MathUtils;
 
public class DynamicCentroidCluster 
{
    private List<ClusterableFragment> points;
    
    private ClusterableFragment centroid;
    
    private boolean updateCentroid = false;
 
//------------------------------------------------------------------------------
    
    public DynamicCentroidCluster()
    {
        this.points = new ArrayList<ClusterableFragment>();
    }
    
//------------------------------------------------------------------------------
    
    public DynamicCentroidCluster(ClusterableFragment centroid)
    {
        this.points = new ArrayList<ClusterableFragment>();
        this.centroid = centroid.clone();
        this.points.add(centroid);
    }
    
//------------------------------------------------------------------------------
    
    public ClusterableFragment getCentroid() 
    {
        if (updateCentroid)
        {
            List<double[]> membersCoords = new ArrayList<double[]>();
            for (ClusterableFragment cf : getPoints())
            {
                membersCoords.add(cf.getPoint());
            }
            double[] refCentroidCoords = MathUtils.centroidOf(membersCoords, 
                    centroid.getPoint().length);
            centroid.setCoordsVector(refCentroidCoords);
            
            updateCentroid = false;
        }
        return centroid;
    }
    
//------------------------------------------------------------------------------
    
    public ClusterableFragment getNearestToCentroid(DistanceMeasure measure)
    {
        if (points.size() == 1)
            return points.get(0);
        
        ClusterableFragment centroid = getCentroid();
        
        ClusterableFragment nearest = null;
        double smallestDistance = Double.MAX_VALUE;
        for (ClusterableFragment cf : points)
        {
            double distance = measure.compute(centroid.getPoint(),cf.getPoint());
            if (distance < smallestDistance)
            {
                nearest = cf;
                smallestDistance = distance;
            }       
        }
        return nearest;
    }
    
//------------------------------------------------------------------------------
    
    public void addPoint(ClusterableFragment point)
    {
        if (centroid == null)
        {
            // First time ever we add a point
            centroid = point.clone();
        } else {
            updateCentroid = true;
        }
        points.add(point);
    }
 
//------------------------------------------------------------------------------
    
    public void removeAll(Collection<ClusterableFragment> points)
    {
        updateCentroid = true;
        points.removeAll(points);
    }
    
//------------------------------------------------------------------------------
    
    public List<ClusterableFragment> getPoints() 
    {
        return points;
    }
 
//------------------------------------------------------------------------------
    
}