public double EuclideanDistance(DataItem data, DataItem mean)
{
double difference = 0;
difference = Math.Pow(data.X - mean.X, 2);
difference += Math.Pow(data.Y - mean.Y, 2);
return Math.Sqrt(difference);
}
static bool ExpandCluster(List<DataItem> points, DataItem p, int clusterId, double eps, int minPts)
{
List<DataItem> seeds = GetRegion(points, p, eps);
if (seeds.Count < minPts) // no core point
{
p.Cluster = Point.NOISE;
return false;
}
else // all points in seeds are density reachable from point 'p'
{
for (int i = 0; i < seeds.Count; i++) seeds[i].Cluster = clusterId;
seeds.Remove(p);
while (seeds.Count > 0)
{
DataItem currentP = seeds[0];
List<DataItem> result = GetRegion(points, currentP, eps);
if (result.Count >= minPts)
{
for (int i = 0; i < result.Count; i++)
{
DataItem resultP = result[i];
if (resultP.Cluster == DataItem.UNCLASSIFIED || resultP.Cluster == DataItem.NOISE)
{
if (resultP.Cluster == Point.UNCLASSIFIED) seeds.Add(resultP);
resultP.Cluster = clusterId;
}
}
}
seeds.Remove(currentP);
}
return true;
}
}
public void Cluster()
{
while (points.Count > 0)
{
Random rnd = new Random();
var index = rnd.Next(0, points.Count);
DataItem center = points[index];
DataItem newCenter = center;
//inside points
List<DataItem> lst = new List<DataItem>();
while (center == newCenter)
{
foreach (var p in points)
{
if (Math.Sqrt(Math.Pow((p.X - center.X), 2) + Math.Pow((p.Y - center.Y), 2)) < R)
{
lst.Add(p);
}
}
//power center
double powerX = 0;
double powerY = 0;
foreach (var p in lst)
{
powerX += p.X;
powerY += p.Y;
}
double powerCenterX = powerX / lst.Count;
double powerCenterY = powerY / lst.Count;
newCenter = new DataItem(powerCenterX, powerCenterY);
}
result.Add(lst);
centers.Add(newCenter);
foreach (var p in lst)
{
points.Remove(p);
}
}
}
static List<DataItem> GetRegion(List<DataItem> points, DataItem p, double eps)
{
List<DataItem> region = new List<DataItem>();
for (int i = 0; i < points.Count; i++)
{
int distSquared = DataItem.DistanceSquared(p, points[i]);
if (distSquared <= eps) region.Add(points[i]);
}
return region;
}
public static int DistanceSquared(DataItem p1, DataItem p2)
{
double diffX = p2.X - p1.X;
double diffY = p2.Y - p1.Y;
return (int) (diffX * diffX + diffY * diffY);
}