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package de.lmu.ifi.dbs.elki.distance.distancefunction.adapter;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2015
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import de.lmu.ifi.dbs.elki.database.query.distance.DistanceQuery;
import de.lmu.ifi.dbs.elki.database.query.similarity.SimilarityQuery;
import de.lmu.ifi.dbs.elki.database.relation.Relation;
import de.lmu.ifi.dbs.elki.distance.distancefunction.DistanceFunction;
import de.lmu.ifi.dbs.elki.distance.similarityfunction.NormalizedSimilarityFunction;
/**
* Adapter from a normalized similarity function to a distance function using
* <code>-log(sim)</code>.
*
* @author Erich Schubert
*
* @apiviz.has Instance
*
* @param <O> object class to process.
*/
public class LnSimilarityAdapter<O> extends AbstractSimilarityAdapter<O> {
/**
* Constructor.
*
* @param similarityFunction Similarity function
*/
public LnSimilarityAdapter(NormalizedSimilarityFunction<? super O> similarityFunction) {
super(similarityFunction);
}
@Override
public <T extends O> DistanceQuery<T> instantiate(Relation<T> database) {
SimilarityQuery<T> similarityQuery = similarityFunction.instantiate(database);
return new Instance<>(database, this, similarityQuery);
}
/**
* Distance function instance
*
* @author Erich Schubert
*
* @param <O> Object type
*/
public static class Instance<O> extends AbstractSimilarityAdapter.Instance<O> {
/**
* Constructor.
*
* @param database Database
* @param parent Parent distance
* @param similarityQuery similarity Query to use
*/
public Instance(Relation<O> database, DistanceFunction<? super O> parent, SimilarityQuery<O> similarityQuery) {
super(database, parent, similarityQuery);
}
@Override
public double transform(double similarity) {
return -Math.log(similarity);
}
}
/**
* Parameterization class.
*
* @author Erich Schubert
*
* @apiviz.exclude
*/
public static class Parameterizer<O> extends AbstractSimilarityAdapter.Parameterizer<O, NormalizedSimilarityFunction<? super O>> {
@Override
protected LnSimilarityAdapter<O> makeInstance() {
return new LnSimilarityAdapter<>(similarityFunction);
}
@Override
protected Class<? extends NormalizedSimilarityFunction<? super O>> getSimilarityRestriction() {
return NORMALIZED_SIMILARITY;
}
}
}
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