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Java example source code file (RandomKeyMutation.java)

This example Java source code file (RandomKeyMutation.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, chromosome, list, mathillegalargumentexception, mutationpolicy, randomkey, randomkeymutation, util

The RandomKeyMutation.java Java example source code

/*
 * 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 java.util.ArrayList;
import java.util.List;

import org.apache.commons.math3.exception.MathIllegalArgumentException;
import org.apache.commons.math3.exception.util.LocalizedFormats;

/**
 * Mutation operator for {@link RandomKey}s. Changes a randomly chosen element
 * of the array representation to a random value uniformly distributed in [0,1].
 *
 * @since 2.0
 */
public class RandomKeyMutation implements MutationPolicy {

    /**
     * {@inheritDoc}
     *
     * @throws MathIllegalArgumentException if <code>original is not a {@link RandomKey} instance
     */
    public Chromosome mutate(final Chromosome original) throws MathIllegalArgumentException {
        if (!(original instanceof RandomKey<?>)) {
            throw new MathIllegalArgumentException(LocalizedFormats.RANDOMKEY_MUTATION_WRONG_CLASS,
                                                   original.getClass().getSimpleName());
        }

        RandomKey<?> originalRk = (RandomKey) original;
        List<Double> repr = originalRk.getRepresentation();
        int rInd = GeneticAlgorithm.getRandomGenerator().nextInt(repr.size());

        List<Double> newRepr = new ArrayList (repr);
        newRepr.set(rInd, GeneticAlgorithm.getRandomGenerator().nextDouble());

        return originalRk.newFixedLengthChromosome(newRepr);
    }

}

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