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/*
* 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;
import java.util.random.RandomGenerator;
import io.jenetics.AbstractAlterer;
import io.jenetics.Chromosome;
import io.jenetics.Gene;
import io.jenetics.Mutator;
import io.jenetics.MutatorResult;
import io.jenetics.internal.math.Subsets;
import io.jenetics.util.MSeq;
/**
* The reverse sequence mutation, two positions i and j are randomly chosen The
* gene order in a chromosome will then be reversed between this two points.
* This mutation operator can also be used for combinatorial problems, where no
* duplicated genes within a chromosome are allowed, e.g., for the TSP.
*
* @see io.jenetics.SwapMutator
*
* @author Franz Wilhelmstötter
* @version 5.0
* @since 5.0
*/
public class RSMutator<
G extends Gene,
C extends Comparable
>
extends Mutator
{
/**
* Constructs an alterer with a given recombination probability.
*
* @param probability the crossover probability.
* @throws IllegalArgumentException if the {@code probability} is not in the
* valid range of {@code [0, 1]}.
*/
public RSMutator(final double probability) {
super(probability);
}
/**
* Default constructor, with default mutation probability
* ({@link AbstractAlterer#DEFAULT_ALTER_PROBABILITY}).
*/
public RSMutator() {
this(DEFAULT_ALTER_PROBABILITY);
}
@Override
protected MutatorResult> mutate(
final Chromosome chromosome,
final double p,
final RandomGenerator random
) {
final MutatorResult> result;
if (chromosome.length() > 1) {
final int[] points = Subsets.next(random, chromosome.length() + 1, 2);
final MSeq genes = MSeq.of(chromosome);
genes.subSeq(points[0], points[1]).reverse();
result = new MutatorResult<>(
chromosome.newInstance(genes.toISeq()),
points[1] - points[0] - 1
);
} else {
result = new MutatorResult<>(chromosome, 0);
}
return result;
}
}