001/*
002 * Java Genetic Algorithm Library (jenetics-8.3.0).
003 * Copyright (c) 2007-2025 Franz Wilhelmstötter
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License");
006 * you may not use this file except in compliance with the License.
007 * You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 *
017 * Author:
018 *    Franz Wilhelmstötter (franz.wilhelmstoetter@gmail.com)
019 */
020package io.jenetics;
021
022import static java.util.Objects.requireNonNull;
023
024import java.util.random.RandomGenerator;
025
026import io.jenetics.stat.Sampler;
027import io.jenetics.util.DoubleRange;
028
029/**
030 * A mutator which replaces a gene (mutates it) with a value created by a
031 * {@link Sampler}.
032 *
033 * @param <G> the gene type
034 * @param <C> the allele type
035 *
036 * @author <a href="mailto:franz.wilhelmstoetter@gmail.com">Franz Wilhelmstötter</a>
037 * @since 8.3
038 * @version 8.3
039 */
040public class SamplerMutator<
041        G extends NumericGene<?, G>,
042        C extends Comparable<? super C>
043>
044        extends Mutator<G, C>
045{
046
047        protected final Sampler sampler;
048
049        /**
050         * Create a new mutator with the given mutation {@code probability} and
051         * gene {@code sampler}.
052         *
053         * @param probability the mutation probability
054         * @param sampler the gene sampler for creating new gene values
055         */
056        public SamplerMutator(final double probability, final Sampler sampler) {
057                super(probability);
058                this.sampler = requireNonNull(sampler);
059        }
060
061        /**
062         * Create a new mutator with the default mutation probability
063         * {@link #DEFAULT_ALTER_PROBABILITY} and gene {@code sampler}.
064         *
065         * @param sampler the gene sampler for creating new gene values
066         */
067        public SamplerMutator(final Sampler sampler) {
068                this(DEFAULT_ALTER_PROBABILITY, sampler);
069        }
070
071        /**
072         * Create a new mutator with the given mutation {@code probability} and
073         * uniform gene sample, {@link Sampler#UNIFORM}.
074         *
075         * @param probability the mutation probability
076         */
077        public SamplerMutator(final double probability) {
078                this(probability, Sampler.UNIFORM);
079        }
080
081        @Override
082        protected G mutate(final G gene, final RandomGenerator random) {
083                if (!gene.isValid()) {
084                        return gene;
085                }
086
087                final var range = new DoubleRange(
088                        gene.min().doubleValue(),
089                        gene.max().doubleValue()
090                );
091                final var next = sampler.sample(random, range);
092                return Double.isNaN(next) ? gene : gene.newInstance(next);
093        }
094
095}