/// <summary>
/// Generate random points clumped into individual, well-separated, Gaussian clusters with optional uniform noise added.
///
/// </summary>
/// <returns>Points that are grouped into clusters and stored in a Classification.</returns>
public Classification <UnsignedPoint, string> MakeClusters()
{
var clusters = new Classification <UnsignedPoint, string>();
r = new FastRandom();
//var z = new ZigguratGaussianSampler();
var farthestDistanceFromClusterCenter = 0.0;
var minDistance = EllipsoidalGenerator.MinimumSeparation(MaxDistanceStdDev, Dimensions);
var centerGenerator = new DiffuseGenerator(Dimensions, minDistance)
{
// Keep the centers of the clusters away from the edge, so that points do not go out of bounds and have their coordinates truncated.
Minimum = MaxDistanceStdDev,
Maximum = MaxCoordinate - MaxDistanceStdDev
};
var iCluster = 0;
var clusterCenters = new Dictionary <string, UnsignedPoint> ();
foreach (var clusterCenter in centerGenerator.Take(ClusterCount).Where(ctr => ctr != null))
{
var centerPoint = new UnsignedPoint(clusterCenter);
// The cluster size may be random, or come from ClusterSizes.
int clusterSize;
if (ClusterSizes.Length > 0)
{
clusterSize = ClusterSizes[iCluster % ClusterSizes.Length];
}
else
{
clusterSize = r.Next(MinClusterSize, MaxClusterSize);
}
var pointGenerator = new EllipsoidalGenerator(clusterCenter, RandomDoubles(Dimensions, MinDistanceStdDev, MaxDistanceStdDev, r), Dimensions);
var clusterId = iCluster.ToString();
foreach (var iPoint in Enumerable.Range(1, clusterSize))
{
UnsignedPoint p;
clusters.Add(
p = new UnsignedPoint(pointGenerator.Generate(new int[Dimensions])),
clusterId
);
var distance = Math.Sqrt(centerPoint.Measure(p));
farthestDistanceFromClusterCenter = Math.Max(farthestDistanceFromClusterCenter, distance);
}
clusterCenters[clusterId] = centerPoint;
iCluster++;
}
AddNoise((int)Math.Floor(clusters.NumPoints * NoisePercentage / 100), clusterCenters, clusters);
Debug.WriteLine("Test data: Farthest Distance from center = {0:N2}. Minimum Distance Permitted between Clusters = {1:N2}. Max Standard Deviation = {2}",
farthestDistanceFromClusterCenter,
minDistance,
MaxDistanceStdDev
);
return(clusters);
}
/// <summary>
/// Create two random clusters that may be separated from one another by enough distance
/// that they do not overlap, or be partly overlapping, or fully overlapping.
///
/// NOTE: This type of setup is to test divisive clustering, that divides two partly mixed gaussians.
/// </summary>
/// <param name="overlapPercent">A number from zero to 100.
/// If zero, the clusters do not overlap at all.
/// If fifty, then the clusters partly overlap.
/// If 100, the clusters have the same center, so are indistinguishable.</param>
/// <returns>The two clusters.</returns>
public Classification <UnsignedPoint, string> TwoClusters(double overlapPercent)
{
var clusters = new Classification <UnsignedPoint, string>();
r = new FastRandom();
var farthestDistanceFromClusterCenter = 0.0;
var minDistance = EllipsoidalGenerator.MinimumSeparation(MaxDistanceStdDev, Dimensions);
var centerGenerator = new DiffuseGenerator(Dimensions, minDistance)
{
// Keep the centers of the clusters away from the edge, so that points do not go out of bounds and have their coordinates truncated.
// Keep the maximum coordinate farther away, because we will pick the second point by shifting one coordinate
// in the higher direction.
Minimum = MaxDistanceStdDev,
Maximum = MaxCoordinate - MaxDistanceStdDev - (int)minDistance
};
var iCluster = 0;
var clusterCenter1 = centerGenerator.Take(1).FirstOrDefault();
var clusterCenter2 = (int[])clusterCenter1.Clone();
clusterCenter2[0] += (int)(minDistance * (100.0 - overlapPercent) / 100.0);
var centers = new[] { clusterCenter1, clusterCenter2 };
foreach (var clusterCenter in centers)
{
var centerPoint = new UnsignedPoint(clusterCenter);
var clusterSize = r.Next(MinClusterSize, MaxClusterSize);
var pointGenerator = new EllipsoidalGenerator(clusterCenter, RandomDoubles(Dimensions, MinDistanceStdDev, MaxDistanceStdDev, r), Dimensions);
var clusterId = iCluster.ToString();
foreach (var iPoint in Enumerable.Range(1, clusterSize))
{
UnsignedPoint p;
clusters.Add(
p = new UnsignedPoint(pointGenerator.Generate(new int[Dimensions])),
clusterId
);
var distance = Math.Sqrt(centerPoint.Measure(p));
farthestDistanceFromClusterCenter = Math.Max(farthestDistanceFromClusterCenter, distance);
}
iCluster++;
}
//TODO: Go back and recluster the points. Put each point into the cluster whose centroid
// it is nearest. Thus, if two clusters partly overlap, the points from one will be pushed into the other.
return(clusters);
}