Examples with KNNDistanceOrderResult de.lmu.ifi.dbs.elki.algorithm.KNNDistancesSampler.KNNDistanceOrderResult used on opensource projects

Example 1 with KNNDistanceOrderResult

use of de.lmu.ifi.dbs.elki.algorithm.KNNDistancesSampler.KNNDistanceOrderResult in project elki by elki-project.

the class KNNDistancesSampler method run.

/**
 * Provides an order of the kNN-distances for all objects within the specified
 * database.
 *
 * @param database Database
 * @param relation Relation
 * @return Result
 */
public KNNDistanceOrderResult run(Database database, Relation<O> relation) {
    final DistanceQuery<O> distanceQuery = database.getDistanceQuery(relation, getDistanceFunction());
    final KNNQuery<O> knnQuery = database.getKNNQuery(distanceQuery, k + 1);
    final int size = (int) ((sample <= 1.) ? Math.ceil(relation.size() * sample) : sample);
    DBIDs sample = DBIDUtil.randomSample(relation.getDBIDs(), size, rnd);
    FiniteProgress prog = LOG.isVerbose() ? new FiniteProgress("Sampling kNN distances", size, LOG) : null;
    double[] knnDistances = new double[size];
    int i = 0;
    for (DBIDIter iditer = sample.iter(); iditer.valid(); iditer.advance(), i++) {
        final KNNList neighbors = knnQuery.getKNNForDBID(iditer, k + 1);
        knnDistances[i] = neighbors.getKNNDistance();
        LOG.incrementProcessed(prog);
    }
    LOG.ensureCompleted(prog);
    return new KNNDistanceOrderResult(knnDistances, k);
}