/// <summary>
/// Evaluates all given <see cref="ClusterSet{TInstance}" />s according to the given
/// <see cref="IExternalEvaluationCriterion{TInstance, TClass}" />.
/// </summary>
/// <param name="clustering">The cluster-sets to be evaluated.</param>
/// <param name="criterion">The criterion used to evaluate the cluster-sets.</param>
/// <param name="instanceClasses">The instances' classes.</param>
/// <param name="maxClusters">The maximum number of clusters allowed for a cluster-set for it to be evaluated.</param>
/// <returns>A list containing the evaluations for each cluster-set.</returns>
/// <typeparam name="TInstance">The type of instance considered.</typeparam>
/// <typeparam name="TClass">The type of class considered.</typeparam>
public static ICollection <ClusterSetEvaluation <TInstance> > EvaluateClustering <TInstance, TClass>(
this ClusteringResult <TInstance> clustering, IExternalEvaluationCriterion <TInstance, TClass> criterion,
IDictionary <TInstance, TClass> instanceClasses, uint maxClusters) where TInstance : IComparable <TInstance>
{
var evals = new List <ClusterSetEvaluation <TInstance> >();
// checks only one cluster allowed
if (maxClusters == 1)
{
evals.Add(new ClusterSetEvaluation <TInstance>(clustering[0], double.NaN));
return(evals);
}
// evaluates all cluster-sets
foreach (var clusterSet in clustering.Reverse())
{
if (clusterSet.Count < 2 || clusterSet.Count > maxClusters)
{
continue;
}
var eval = criterion.Evaluate(clusterSet, instanceClasses);
evals.Add(new ClusterSetEvaluation <TInstance>(clusterSet, eval));
}
return(evals);
}
/// <summary>
/// Evaluates all given <see cref="ClusterSet{TInstance}" />s according to the given
/// <see cref="IExternalEvaluationCriterion{TInstance,TClass}" />. The maximum number of clusters allowed in a
/// cluster-set for it to be evaluated corresponds to sqrt(N/2), where N is the total number of instances clustered.
/// </summary>
/// <param name="clustering">The cluster-sets to be evaluated.</param>
/// <param name="criterion">The criterion used to evaluate the cluster-sets.</param>
/// <param name="instanceClasses">The instances' classes.</param>
/// <returns>A list containing the evaluations for each cluster-set.</returns>
/// <typeparam name="TInstance">The type of instance considered.</typeparam>
/// <typeparam name="TClass">The type of class considered.</typeparam>
public static ICollection <ClusterSetEvaluation <TInstance> > EvaluateClustering <TInstance, TClass>(
this ClusteringResult <TInstance> clustering, IExternalEvaluationCriterion <TInstance, TClass> criterion,
IDictionary <TInstance, TClass> instanceClasses) where TInstance : IComparable <TInstance> =>
EvaluateClustering(clustering, criterion, instanceClasses, (uint)Math.Sqrt(clustering.Count / 2d));
