/*
* Artificial Intelligence for Humans
* Volume 2: Nature Inspired Algorithms
* Java Version
* http://www.aifh.org
* http://www.jeffheaton.com
*
* Code repository:
* https://github.com/jeffheaton/aifh
*
* Copyright 2014 by Jeff Heaton
*
* 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.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package com.heatonresearch.aifh.genetic.mutate;
import com.heatonresearch.aifh.evolutionary.genome.Genome;
import com.heatonresearch.aifh.evolutionary.opp.EvolutionaryOperator;
import com.heatonresearch.aifh.evolutionary.train.EvolutionaryAlgorithm;
import com.heatonresearch.aifh.genetic.genome.DoubleArrayGenome;
import com.heatonresearch.aifh.randomize.GenerateRandom;
/**
* A simple mutation based on random numbers.
*/
public class MutatePerturb implements EvolutionaryOperator {
/**
* The amount to perturb by.
*/
private final double perturbAmount;
/**
* Construct a perturb mutation.
*
* @param thePerturbAmount The amount to mutate by(percent).
*/
public MutatePerturb(final double thePerturbAmount) {
this.perturbAmount = thePerturbAmount;
}
/**
* {@inheritDoc}
*/
@Override
public void performOperation(GenerateRandom rnd, Genome[] parents, int parentIndex,
Genome[] offspring, int offspringIndex) {
DoubleArrayGenome parent = (DoubleArrayGenome) parents[parentIndex];
offspring[offspringIndex] = parent.getPopulation().getGenomeFactory().factor();
DoubleArrayGenome child = (DoubleArrayGenome) offspring[offspringIndex];
for (int i = 0; i < parent.size(); i++) {
double value = parent.getData()[i];
value += value * (perturbAmount - (rnd.nextDouble() * perturbAmount * 2));
child.getData()[i] = value;
}
}
/**
* @return The number of offspring produced, which is 1 for this mutation.
*/
@Override
public int offspringProduced() {
return 1;
}
/**
* {@inheritDoc}
*/
@Override
public int parentsNeeded() {
return 1;
}
/**
* {@inheritDoc}
*/
@Override
public void init(EvolutionaryAlgorithm theOwner) {
// not needed
}
}