Examples with GrahamScanConvexHull2D de.lmu.ifi.dbs.elki.math.geometry.GrahamScanConvexHull2D used on opensource projects

Example 1 with GrahamScanConvexHull2D

use of de.lmu.ifi.dbs.elki.math.geometry.GrahamScanConvexHull2D in project elki by elki-project.

the class KMLOutputHandler method buildHullsRecursively.

/**
 * Recursively step through the clusters to build the hulls.
 *
 * @param clu Current cluster
 * @param hier Clustering hierarchy
 * @param hulls Hull map
 */
private DoubleObjPair<Polygon> buildHullsRecursively(Cluster<Model> clu, Hierarchy<Cluster<Model>> hier, Map<Object, DoubleObjPair<Polygon>> hulls, Relation<? extends NumberVector> coords) {
    final DBIDs ids = clu.getIDs();
    GrahamScanConvexHull2D hull = new GrahamScanConvexHull2D();
    for (DBIDIter iter = ids.iter(); iter.valid(); iter.advance()) {
        hull.add(coords.get(iter).toArray());
    }
    double weight = ids.size();
    if (hier != null && hulls != null) {
        final int numc = hier.numChildren(clu);
        if (numc > 0) {
            for (It<Cluster<Model>> iter = hier.iterChildren(clu); iter.valid(); iter.advance()) {
                final Cluster<Model> iclu = iter.get();
                DoubleObjPair<Polygon> poly = hulls.get(iclu);
                if (poly == null) {
                    poly = buildHullsRecursively(iclu, hier, hulls, coords);
                }
                // Add inner convex hull to outer convex hull.
                for (ArrayListIter<double[]> vi = poly.second.iter(); vi.valid(); vi.advance()) {
                    hull.add(vi.get());
                }
                weight += poly.first / numc;
            }
        }
    }
    DoubleObjPair<Polygon> pair = new DoubleObjPair<>(weight, hull.getHull());
    hulls.put(clu, pair);
    return pair;
}