public double CompleteLink(Cluster c)
{
// I want to find the greatest distance between this cluster and the cluster given
var longestDistance = double.MinValue;
foreach (var thisPoint in this.Points)
{
foreach (var thatPoint in c.Points)
{
var tmpDist = Point.Distance(thisPoint, thatPoint);
if (tmpDist > longestDistance)
{
longestDistance = tmpDist;
}
}
}
return longestDistance;
}
public double MeanLink(Cluster c)
{
var thisMeanPoint = new Point { X = 0, Y = 0 };
foreach (var thisPoint in this.Points)
{
thisMeanPoint.X = thisMeanPoint.X + thisPoint.X;
thisMeanPoint.Y = thisMeanPoint.Y + thisPoint.Y;
}
thisMeanPoint.X = thisMeanPoint.X / this.Points.Count;
thisMeanPoint.Y = thisMeanPoint.Y / this.Points.Count;
var thatMeanPoint = new Point { X = 0, Y = 0 };
foreach (var thatPoint in c.Points)
{
thatMeanPoint.X = thatMeanPoint.X + thatPoint.X;
thatMeanPoint.Y = thatMeanPoint.Y + thatPoint.Y;
}
thatMeanPoint.X = thatMeanPoint.X / c.Points.Count;
thatMeanPoint.Y = thatMeanPoint.Y / c.Points.Count;
return Point.Distance(thisMeanPoint, thatMeanPoint);
}
public double SingleLink(Cluster c)
{
// I want to find the shortest distance between this cluster and the cluster given
var shortestDistance = double.MaxValue;
foreach (var thisPoint in this.Points)
{
foreach (var thatPoint in c.Points)
{
var tmpDist = Point.Distance(thisPoint, thatPoint);
if (tmpDist < shortestDistance)
{
shortestDistance = tmpDist;
}
}
}
return shortestDistance;
}
public void MergeClusters(Cluster c)
{
foreach (var cPoint in c.Points)
{
this.AddPoint(cPoint);
}
}
private static void Links(IEnumerable<Point> points)
{
var singleLinkClusters = new List<Cluster>();
var completeLinkClusters = new List<Cluster>();
var meanLinkClusters = new List<Cluster>();
foreach (var point in points)
{
var cluster = new Cluster();
cluster.AddPoint(point);
singleLinkClusters.Add(cluster);
var cCluster = new Cluster();
cCluster.AddPoint(new Point
{
Id = point.Id,
X = point.X,
Y = point.Y
});
completeLinkClusters.Add(cCluster);
var mCluster = new Cluster();
mCluster.AddPoint(new Point
{
Id = point.Id,
X = point.X,
Y = point.Y
});
meanLinkClusters.Add(mCluster);
}
//find the smallest distance between all clusters
SingleLinkCluster(singleLinkClusters);
CompleLinkCluster(completeLinkClusters);
MeanLinkCluster(meanLinkClusters);
}
private static Tuple<double, string, List<Cluster>> KMeansPlusPlus(IList<Point> points)
{
var phi = new int[points.Count];
//choose c1 in X arbitrarily
var clusters = new Point[3];
clusters[0] = points[0];
//get a random
//select 1 random points
var threeCenterCost = 0.0;
for (var i = 1; i < 3; i++)
{
var prevCluster = clusters[i - 1];
//choose ci from X with a probability proportional to d(x, phic-1(x))^2
var probTuples = new List<Tuple<Point, double>>();
for (var j = 0; j < points.Count; j++)
{
var dist = Point.Distance(points[j], prevCluster);
probTuples.Add(new Tuple<Point, double>(points[j], dist * dist));
}
var total = probTuples.Sum(t => t.Item2);
var nextCluster = Random.NextDouble();
var runningTotal = (double)0;
foreach (var tuple in probTuples)
{
runningTotal += tuple.Item2 / total;
if (nextCluster <= runningTotal)
{
clusters[i] = tuple.Item1;
threeCenterCost += tuple.Item2;
break;
}
}
}
for (var i = 0; i < points.Count; i++)
{
if (clusters.Any(t => t.Id == points[i].Id))
{
continue;
}
var m = double.MaxValue;
for (var j = 0; j < clusters.Length; j++)
{
var dist = Point.Distance(points[i], clusters[j]);
if (dist < m)
{
phi[i] = j;
m = dist;
}
}
}
var sb = new StringBuilder();
for (var i = 0; i < clusters.Length; i++)
{
for (var j = 0; j < points.Count; j++)
{
if (phi[j] == i)
{
sb.AppendLine(points[j].ToString());
}
}
sb.AppendLine();
}
var c1 = new Cluster();
var c2 = new Cluster();
var c3 = new Cluster();
c1.AddPoint(clusters[0]);
c2.AddPoint(clusters[1]);
c3.AddPoint(clusters[2]);
return new Tuple<double, string, List<Cluster>>(
threeCenterCost, sb.ToString(), new List<Cluster> { c1, c2, c3 });
}
private static void KMeans(ICollection<Point> points)
{
// initially choose k points that are likely to be in different clusters
// to avoid too much variation in the results, choose c1 as the point a
var p1 = points.First(t => t.Id == "a");
Point p2 = null;
Point p3 = null;
// find the point that has the largest distance from c1
var largestTuple = FindLargestDistanceFromPointTuple(points, p1);
if (largestTuple.Item1 == null)
{
return;
}
p2 = largestTuple.Item1;
var tempPoint = new Point
{
X = (p1.X + p2.X) / 2,
Y = (p1.Y + p2.Y) / 2,
};
largestTuple = FindLargestDistanceFromPointTuple(points, tempPoint);
if (largestTuple.Item1 == null)
{
return;
}
p3 = largestTuple.Item1;
var clusters = new List<Cluster>();
var initClusters = new[] { p1, p2, p3 };
foreach (var point in initClusters)
{
var cluster = new Cluster();
cluster.AddPoint(point);
clusters.Add(cluster);
}
// copy to new array, this is a waste I know..
foreach (var point in points)
{
if (initClusters.Any(t => t.Id == point.Id))
{
continue;
}
var closestCluster = new Tuple<Cluster, double>(null, double.MaxValue);
foreach (var cluster in clusters)
{
var dist = Point.Distance(cluster.Centroid, point);
if (dist < closestCluster.Item2)
{
closestCluster = new Tuple<Cluster, double>(cluster, dist);
}
}
if (closestCluster.Item1 != null)
{
closestCluster.Item1.AddPoint(point);
}
}
PrintClusters(clusters);
}
private static Tuple<double, string, List<Cluster>> Gonzales3Center(IList<Point> points)
{
var phi = new int[points.Count];
var cost = 0.0;
for (var i = 0; i < points.Count; i++)
{
phi[i] = 0;
}
var cPhi = new Point[3];
cPhi[0] = points[0];
var m1 = (double)0;
cPhi[1] = points[0];
// find the furthest point from A
foreach (var point in points)
{
var dist = Point.Distance(point, cPhi[0]);
if (dist > m1)
{
m1 = dist;
cPhi[1] = point;
}
}
cost += m1;
// update all the clusters now to be in either 1 or 2
for (var i = 0; i < points.Count; i++)
{
var point = points[i];
var dist1 = Point.Distance(point, cPhi[0]);
var dist2 = Point.Distance(point, cPhi[1]);
if (dist1 > dist2)
{
phi[i] = 1;
}
}
var tempCenter = new Point { X = (cPhi[0].X + cPhi[1].X) / 2, Y = (cPhi[0].Y + cPhi[1].Y) / 2 };
var furthestCluster = GonzalezFurthestCluster(points, phi, tempCenter);
cPhi[2] = points[furthestCluster.Item1];
//var furthestCluster1 = GonzalezFurthestCluster(points, phi, cPhi[0]);
//var furthestCluster2 = GonzalezFurthestCluster(points, phi, cPhi[1]);
//if (furthestCluster1.Item2 > furthestCluster2.Item2)
//{
// cPhi[2] = points[furthestCluster1.Item1];
//}
//else
//{
// cPhi[2] = points[furthestCluster2.Item1];
//}
for (var j = 0; j < points.Count; j++)
{
var m = double.MaxValue;
for (var i = 0; i < 3; i++)
{
var dist = Point.Distance(points[j], cPhi[i]);
if (dist < m)
{
m = dist;
phi[j] = i;
}
}
}
cost += m1;
var sb = new StringBuilder();
for (var i = 0; i < cPhi.Length; i++)
{
for (var j = 0; j < points.Count; j++)
{
if (phi[j] == i)
{
sb.AppendLine(points[j].ToString());
}
}
sb.AppendLine();
}
var c1 = new Cluster();
c1.AddPoint(cPhi[0]);
var c2 = new Cluster();
c2.AddPoint(cPhi[1]);
var c3 = new Cluster();
c3.AddPoint(cPhi[2]);
return new Tuple<double, string, List<Cluster>>(cost, sb.ToString(), new List<Cluster> { c1, c2, c3 });
}