static List <DBSCANElement> GetRegion(List <DBSCANElement> elementSet, DBSCANElement p, double eps)
{
List <DBSCANElement> region = new List <DBSCANElement>();
for (int i = 0; i < elementSet.Count; i++)
{
int dist = DBSCANElement.Distance(p, elementSet[i]);
if (dist <= eps)
{
region.Add(elementSet[i]);
}
}
return(region);
}
static bool ExpandCluster(List <DBSCANElement> elementSet, DBSCANElement p, int clusterId, double eps, int minElements)
{
List <DBSCANElement> seeds = GetRegion(elementSet, p, eps);
if (seeds.Count < minElements) // no core point
{
p.ClusterId = DBSCANElement.NOISE;
return(false);
}
else // all points in seeds are density reachable from point 'p'
{
for (int i = 0; i < seeds.Count; i++)
{
seeds[i].ClusterId = clusterId;
}
seeds.Remove(p);
while (seeds.Count > 0)
{
DBSCANElement currentP = seeds[0];
List <DBSCANElement> result = GetRegion(elementSet, currentP, eps);
if (result.Count >= minElements)
{
for (int i = 0; i < result.Count; i++)
{
DBSCANElement resultP = result[i];
if (resultP.ClusterId == DBSCANElement.UNCLASSIFIED || resultP.ClusterId == DBSCANElement.NOISE)
{
if (resultP.ClusterId == DBSCANElement.UNCLASSIFIED)
{
seeds.Add(resultP);
}
resultP.ClusterId = clusterId;
}
}
}
seeds.Remove(currentP);
}
return(true);
}
}
static List <List <DBSCANElement> > GetClusters(List <DBSCANElement> elementSet, double eps, int minElements)
{
if (elementSet == null)
{
return(null);
}
List <List <DBSCANElement> > clusters = new List <List <DBSCANElement> >();
int clusterId = 1;
for (int i = 0; i < elementSet.Count; i++)
{
DBSCANElement p = elementSet[i];
if (p.ClusterId == DBSCANElement.UNCLASSIFIED)
{
if (ExpandCluster(elementSet, p, clusterId, eps, minElements))
{
clusterId++;
}
}
}
// sort out points into their clusters, if any
int maxClusterId = elementSet.OrderBy(p => p.ClusterId).Last().ClusterId;
if (maxClusterId < 1)
{
return(clusters); // no clusters, so list is empty
}
for (int i = 0; i < maxClusterId; i++)
{
clusters.Add(new List <DBSCANElement>());
}
foreach (DBSCANElement p in elementSet)
{
if (p.ClusterId > 0)
{
clusters[p.ClusterId - 1].Add(p);
}
}
return(clusters);
}
public static int Distance(DBSCANElement p1, DBSCANElement p2)
{
return(MatchingMachine.GetHammingDis(p1.Value, p2.Value));
}