io.jenetics.ext.moea.CrowdedComparator Maven / Gradle / Ivy
The newest version!
/*
* Java Genetic Algorithm Library (jenetics-8.1.0).
* Copyright (c) 2007-2024 Franz Wilhelmstötter
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* Author:
* Franz Wilhelmstötter ([email protected])
*/
package io.jenetics.ext.moea;
import java.util.Comparator;
import java.util.function.ToIntFunction;
import io.jenetics.Optimize;
import io.jenetics.internal.util.IntComparator;
import io.jenetics.util.BaseSeq;
/**
* Crowded distance comparator.
*
* @author Franz Wilhelmstötter
* @version 4.1
* @since 4.1
*/
final class CrowdedComparator implements IntComparator {
private final int[] _rank;
private final double[] _dist;
CrowdedComparator(
final BaseSeq population,
final Optimize opt,
final Comparator dominance,
final ElementComparator comparator,
final ElementDistance distance,
final ToIntFunction dimension
) {
_rank = Pareto.rank(
population,
opt == Optimize.MAXIMUM
? dominance
: dominance.reversed()
);
_dist = Pareto.crowdingDistance(
population,
opt == Optimize.MAXIMUM
? comparator
: comparator.reversed(),
distance,
dimension
);
}
@Override
public int compare(final int i, final int j) {
if (cco(i, j)) {
return 1;
} else if (cco(j, i)) {
return -1;
} else {
return 0;
}
}
private boolean cco(final int i, final int j) {
return _rank[i] < _rank[j] ||
(_rank[i] == _rank[j] && _dist[i] > _dist[j]);
}
}