public double SquaredError(CentroidItem centroid, IEnumerable <Client> PointsInCluster)
{
double amount = .0;
foreach (var point in PointsInCluster)
{
amount += Math.Pow(point.Distance(centroid.Data), 2);
}
return(amount);
}
public Tuple <Client[], double> Run(Client[] clients, int MaxAmountOfClusters, int MaxAmountOfIterations)
{
var centroidChooserList = clients.ToList();
if (clients.Length < MaxAmountOfClusters)
{
return(null);
}
var changed = true;
var centroids = new List <CentroidItem>();
Random rnd = new Random();
for (int i = 0; i < MaxAmountOfClusters; i++)
{
int randomIndex = rnd.Next(centroidChooserList.Count);
var data = centroidChooserList[randomIndex].Data;
centroidChooserList = centroidChooserList.Where(x => !x.Data.Equals(data)).ToList();
centroids.Add(new CentroidItem(data, i));
}
while (changed && MaxAmountOfIterations != 0)
{
foreach (var client in clients)
{
double lowestDistance = double.PositiveInfinity;
for (int i = 0; i < MaxAmountOfClusters; i++)
{
double distanceBetweenPoints = client.Distance(centroids[i].Data);
if (distanceBetweenPoints < lowestDistance)
{
lowestDistance = distanceBetweenPoints;
client.ClusterNumber = centroids[i].Number;
}
}
}
var centroidWithPoints = clients
.GroupBy(c => c.ClusterNumber)
.ToDictionary(c => c.Key, c => c.ToList());
var centroidNotChangedCount = 0;
foreach (var c in centroidWithPoints)
{
var oldCentroid = centroids.First(x => x.Number == c.Key);
var list = new List <Vector>();
foreach (var client in c.Value)
{
list.Add(client.Data);
}
var newCentroid = new CentroidItem(Mean(list, oldCentroid.Data.Points.Length), c.Key);
if (!oldCentroid.Equals(newCentroid))
{
centroids[newCentroid.Number] = newCentroid;
}
else
{
centroidNotChangedCount++;
}
}
if (centroidNotChangedCount == MaxAmountOfClusters)
{
changed = false;
}
MaxAmountOfIterations--;
}
var sse = .0;
for (int i = 0; i < MaxAmountOfClusters; i++)
{
var clientByClusterId = clients.Where(x => x.ClusterNumber == i);
sse += SquaredError(centroids[i], clientByClusterId);
}
return(Tuple.Create(clients, sse));
}