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package de.lmu.ifi.dbs.elki.distance.distanceresultlist;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2013
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 java.util.Collections;
import java.util.Comparator;
import java.util.List;
import de.lmu.ifi.dbs.elki.database.ids.DBIDUtil;
import de.lmu.ifi.dbs.elki.database.ids.distance.DistanceDBIDList;
import de.lmu.ifi.dbs.elki.database.ids.distance.DistanceDBIDPair;
import de.lmu.ifi.dbs.elki.database.ids.distance.DistanceDBIDListIter;
import de.lmu.ifi.dbs.elki.distance.distancevalue.DoubleDistance;
/**
* Utility classes for distance DBID results.
*
* @author Erich Schubert
*
* @apiviz.uses DistanceDBIDPair oneway - -
*/
public final class DistanceDBIDResultUtil {
/**
* Get a comparator to sort by distance, then DBID
*
* @return comparator
*/
@SuppressWarnings("unchecked")
public static <D extends DistanceDBIDPair<?>> Comparator<? super D> distanceComparator() {
return (Comparator<D>) BY_DISTANCE_THEN_DBID;
}
/**
* Sort a Java list by distance.
*
* @param list List to sort
*/
@SuppressWarnings("unchecked")
public static <D extends DistanceDBIDPair<?>> void sortByDistance(List<? extends D> list) {
Collections.sort(list, (Comparator<D>) BY_DISTANCE_THEN_DBID);
}
/**
* Static comparator.
*/
private static final Comparator<DistanceDBIDPair<?>> BY_DISTANCE_THEN_DBID = new Comparator<DistanceDBIDPair<?>>() {
@SuppressWarnings("unchecked")
@Override
public int compare(DistanceDBIDPair<?> o1, DistanceDBIDPair<?> o2) {
final int d = ((DistanceDBIDPair<DoubleDistance>)o1).compareByDistance((DistanceDBIDPair<DoubleDistance>)o2);
return (d == 0) ? DBIDUtil.compare(o1, o2) : d;
}
};
/**
* Static comparator for heaps.
*/
public static final Comparator<DistanceDBIDPair<?>> BY_REVERSE_DISTANCE = new Comparator<DistanceDBIDPair<?>>() {
@SuppressWarnings("unchecked")
@Override
public int compare(DistanceDBIDPair<?> o1, DistanceDBIDPair<?> o2) {
return -((DistanceDBIDPair<DoubleDistance>)o1).compareByDistance((DistanceDBIDPair<DoubleDistance>)o2);
}
};
public static String toString(DistanceDBIDList<?> res) {
StringBuilder buf = new StringBuilder();
buf.append('[');
DistanceDBIDListIter<?> iter = res.iter();
for(; iter.valid(); iter.advance()) {
if(buf.length() > 1) {
buf.append(',').append(' ');
}
buf.append(iter.getDistancePair().toString());
}
buf.append(']');
return buf.toString();
}
}
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