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Diffstat (limited to 'src/main/java/org/apache/commons/math3/genetics/BinaryMutation.java')
-rw-r--r-- | src/main/java/org/apache/commons/math3/genetics/BinaryMutation.java | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/src/main/java/org/apache/commons/math3/genetics/BinaryMutation.java b/src/main/java/org/apache/commons/math3/genetics/BinaryMutation.java new file mode 100644 index 0000000..9372b13 --- /dev/null +++ b/src/main/java/org/apache/commons/math3/genetics/BinaryMutation.java @@ -0,0 +1,56 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You 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. + */ +package org.apache.commons.math3.genetics; + +import org.apache.commons.math3.exception.MathIllegalArgumentException; +import org.apache.commons.math3.exception.util.LocalizedFormats; + +import java.util.ArrayList; +import java.util.List; + +/** + * Mutation for {@link BinaryChromosome}s. Randomly changes one gene. + * + * @since 2.0 + */ +public class BinaryMutation implements MutationPolicy { + + /** + * Mutate the given chromosome. Randomly changes one gene. + * + * @param original the original chromosome. + * @return the mutated chromosome. + * @throws MathIllegalArgumentException if <code>original</code> is not an instance of {@link + * BinaryChromosome}. + */ + public Chromosome mutate(Chromosome original) throws MathIllegalArgumentException { + if (!(original instanceof BinaryChromosome)) { + throw new MathIllegalArgumentException(LocalizedFormats.INVALID_BINARY_CHROMOSOME); + } + + BinaryChromosome origChrom = (BinaryChromosome) original; + List<Integer> newRepr = new ArrayList<Integer>(origChrom.getRepresentation()); + + // randomly select a gene + int geneIndex = GeneticAlgorithm.getRandomGenerator().nextInt(origChrom.getLength()); + // and change it + newRepr.set(geneIndex, origChrom.getRepresentation().get(geneIndex) == 0 ? 1 : 0); + + Chromosome newChrom = origChrom.newFixedLengthChromosome(newRepr); + return newChrom; + } +} |