EvolutionaryAlgorithm.java

/*
 * Encog(tm) Core v3.4 - Java Version
 * http://www.heatonresearch.com/encog/
 * https://github.com/encog/encog-java-core
 
 * Copyright 2008-2016 Heaton Research, Inc.
 *
 * 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 org.encog.ml.ea.train;

import java.util.List;

import org.encog.ml.CalculateScore;
import org.encog.ml.ea.codec.GeneticCODEC;
import org.encog.ml.ea.genome.Genome;
import org.encog.ml.ea.opp.EvolutionaryOperator;
import org.encog.ml.ea.opp.OperationList;
import org.encog.ml.ea.opp.selection.SelectionOperator;
import org.encog.ml.ea.population.Population;
import org.encog.ml.ea.rules.RuleHolder;
import org.encog.ml.ea.score.AdjustScore;
import org.encog.ml.ea.sort.GenomeComparator;
import org.encog.ml.ea.species.Speciation;

/**
 * This interface defines the basic functionality of an Evolutionary Algorithm.
 * An evolutionary algorithm is one that applies operations to a population of
 * potential "solutions".
 */
public interface EvolutionaryAlgorithm {

	/**
	 * Add an operation.
	 * 
	 * @param probability
	 *            The probability of using this operator.
	 * @param opp
	 *            The operator to add.
	 */
	void addOperation(double probability, EvolutionaryOperator opp);

	/**
	 * Add a score adjuster. Score adjusters are used to adjust the adjusted
	 * score of a genome. This allows bonuses and penalties to be applied for
	 * desirable or undesirable traits.
	 * 
	 * @param scoreAdjust
	 *            The score adjustor to add.
	 */
	void addScoreAdjuster(AdjustScore scoreAdjust);

	/**
	 * Calculate the score for a genome.
	 * 
	 * @param g
	 *            The genome to calculate the score for.
	 */
	void calculateScore(Genome g);

	/**
	 * Called when training is finished. This allows the EA to properly shut
	 * down.
	 */
	void finishTraining();

	/**
	 * Get the comparator that is used to choose the "true best" genome. This
	 * uses the real score, and not the adjusted score.
	 * 
	 * @return The best comparator.
	 */
	GenomeComparator getBestComparator();

	/**
	 * @return The current best genome. This genome is safe to use while the EA
	 *         is running. Genomes are not modified. They simply produce
	 *         "offspring".
	 */
	Genome getBestGenome();

	/**
	 * @return The CODEC that is used to transform between genome and phenome.
	 */
	GeneticCODEC getCODEC();

	/**
	 * @return The current score. This value should either be minimized or
	 *         maximized, depending on the score function.
	 */
	double getError();

	/**
	 * @return The current iteration number. Also sometimes referred to as
	 *         generation or epoch.
	 */
	int getIteration();

	/**
	 * @return The maximum size an individual genome can be. This is an
	 *         arbitrary number defined by the genome. Lower numbers are less
	 *         complex.
	 */
	int getMaxIndividualSize();

	/**
	 * @return The maximum number to try certain genetic operations. This
	 *         prevents endless loops.
	 */
	int getMaxTries();

	/**
	 * @return The operators.
	 */
	OperationList getOperators();

	/**
	 * @return The population.
	 */
	Population getPopulation();

	/**
	 * @return The score adjusters. This allows bonuses and penalties to be
	 *         applied for desirable or undesirable traits.
	 */
	List<AdjustScore> getScoreAdjusters();

	/**
	 * @return The score function.
	 */
	CalculateScore getScoreFunction();

	/**
	 * @return The selection operator. Used to choose genomes.
	 */
	public SelectionOperator getSelection();

	/**
	 * Get the comparator that is used to choose the "best" genome for
	 * selection, as opposed to the "true best". This uses the adjusted score,
	 * and not the score.
	 * 
	 * @return The selection comparator.
	 */
	GenomeComparator getSelectionComparator();

	/**
	 * @return True if exceptions that occur during genetic operations should be
	 *         ignored.
	 */
	boolean getShouldIgnoreExceptions();

	/**
	 * @return The speciation method.
	 */
	Speciation getSpeciation();

	/**
	 * @return True if any genome validators should be applied.
	 */
	boolean isValidationMode();

	/**
	 * Perform a training iteration. Also called generations or epochs.
	 */
	void iteration();

	/**
	 * Set the comparator that is used to choose the "true best" genome. This
	 * uses the real score, and not the adjusted score.
	 * 
	 * @param bestComparator
	 *            The best comparator.
	 */
	void setBestComparator(GenomeComparator bestComparator);

	/**
	 * Set the population.
	 * 
	 * @param thePopulation
	 *            The population.
	 */
	void setPopulation(Population thePopulation);

	/**
	 * Set the selection operator.
	 * 
	 * @param selection
	 *            The selection operator.
	 */
	public void setSelection(SelectionOperator selection);

	/**
	 * Set the comparator that is used to choose the "best" genome for
	 * selection, as opposed to the "true best". This uses the adjusted score,
	 * and not the score.
	 * 
	 * @param selectionComparator
	 *            The selection comparator.
	 */
	void setSelectionComparator(GenomeComparator selectionComparator);

	/**
	 * Determines if genetic operator exceptions should be ignored.
	 * 
	 * @param b
	 *            True if exceptions should be ignored.
	 */
	void setShouldIgnoreExceptions(boolean b);

	/**
	 * Set the speciation method.
	 * 
	 * @param m
	 *            The speciation method.
	 */
	void setSpeciation(Speciation m);

	/**
	 * Determine if the genomes should be validated. This takes more time but
	 * can help isolate a problem.
	 * 
	 * @param validationMode
	 *            True, if validation mode is enabled.
	 */
	void setValidationMode(boolean validationMode);

}