public static double SilhouetteIndex(ClusteredItem datum, Partition clusters)
{
//Calculate A
double distA = 0.0;
KPoint datumPoint = clusters.Points[datum.Id];
foreach (ClusteredItem d in clusters.Clusters[datum.ClusterId].Points)
{
distA += datumPoint.elucideanDistance(clusters.Points[d.Id]);
}
distA /= (double)(clusters.Clusters[datum.ClusterId].Points.Count - 1);
double minB = double.MaxValue;
for (int i = 0; i < clusters.Clusters.Count; i++)
{
if (i != datum.ClusterId)
{
double distB = 0.0;
foreach (ClusteredItem d in clusters.Clusters[i].Points)
{
distB += datumPoint.elucideanDistance(clusters.Points[d.Id]);
}
distB /= (double)(clusters.Clusters[i].Points.Count);
if (distB < minB)
{
minB = distB;
}
}
}
return((minB - distA) / Math.Max(minB, distA));
}
public MinHeapPriorityQueue <KPoint> NearestNeighbors(KPoint p, int k, MinHeapPriorityQueue <KPoint> Q, BallTreeNode B)
{
if (p[B.PivotDim] > Q.peek().elucideanDistance(p))
{
return(Q);
}
else if (B.IsLeaf())
{
if (p.elucideanDistance(B.Point) < p.elucideanDistance(Q.peek()))
{
if (Q.Count >= k)
{
Q.extractMin();
}
}
}
return(Q);
}
