/// <summary>
/// Merges the small outlier clusters with nearby larger clusters.
/// </summary>
/// <returns>The number of outlier clusters merged.</returns>
/// <param name="maxOutlierMergeDistance">An outlier will only be merged if its distance from
/// its nearest cluster does not exceed this square distance.</param>
public int MergeOutliers(long maxOutlierMergeDistance)
{
var mergesDone = 0;
var cc = new ClosestCluster <string>(Clusters);
var closeOutlierPairs = cc.FindClosestOutliers(
MaxNeighborsToCompare,
maxOutlierMergeDistance,
OutlierSize
);
foreach (var pair in closeOutlierPairs)
{
pair.Relabel(Clusters);
// We do not want an outlier to cause the merger of two large clusters
// if each of the large clusters is near the outlier but not near each other.
// Thus, once the outlier is merged with the nearer of its neighbors,
// it will be ruled out from firther merges.
if (pair.CountOutliers(Clusters, OutlierSize) != 1)
{
continue;
}
if (Clusters.Merge(pair.Color1, pair.Color2))
{
mergesDone++;
}
}
return(mergesDone);
}
/// <summary>
/// Merges the outliers to their nearest neighboring large cluster.
/// In this case, any cluster smaller than UnmergeableSize is considered an outlier.
/// </summary>
private void MergeOutliers()
{
var cc = new ClosestCluster <string>(Clusters);
foreach (var cp in cc.FindClosestOutliers(Clusters.NumPartitions, long.MaxValue, UnmergeableSize))
{
Merge(cp.Point1, cp.Point2);
}
}
