001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  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 */
017package org.apache.commons.math4.genetics;
018
019import java.util.ArrayList;
020import java.util.Collection;
021import java.util.Collections;
022import java.util.Iterator;
023import java.util.List;
024
025import org.apache.commons.math4.exception.NotPositiveException;
026import org.apache.commons.math4.exception.NullArgumentException;
027import org.apache.commons.math4.exception.NumberIsTooLargeException;
028import org.apache.commons.math4.exception.NumberIsTooSmallException;
029import org.apache.commons.math4.exception.util.LocalizedFormats;
030
031/**
032 * Population of chromosomes represented by a {@link List}.
033 *
034 * @since 2.0
035 */
036public abstract class ListPopulation implements Population {
037
038    /** List of chromosomes */
039    private final List<Chromosome> chromosomes;
040
041    /** maximal size of the population */
042    private int populationLimit;
043
044    /**
045     * Creates a new ListPopulation instance and initializes its inner chromosome list.
046     *
047     * @param populationLimit maximal size of the population
048     * @throws NotPositiveException if the population limit is not a positive number (&lt; 1)
049     */
050    public ListPopulation(final int populationLimit) throws NotPositiveException {
051        this(Collections.<Chromosome> emptyList(), populationLimit);
052    }
053
054    /**
055     * Creates a new ListPopulation instance.
056     * <p>
057     * Note: the chromosomes of the specified list are added to the population.
058     *
059     * @param chromosomes list of chromosomes to be added to the population
060     * @param populationLimit maximal size of the population
061     * @throws NullArgumentException if the list of chromosomes is {@code null}
062     * @throws NotPositiveException if the population limit is not a positive number (&lt; 1)
063     * @throws NumberIsTooLargeException if the list of chromosomes exceeds the population limit
064     */
065    public ListPopulation(final List<Chromosome> chromosomes, final int populationLimit)
066        throws NullArgumentException, NotPositiveException, NumberIsTooLargeException {
067
068        if (chromosomes == null) {
069            throw new NullArgumentException();
070        }
071        if (populationLimit <= 0) {
072            throw new NotPositiveException(LocalizedFormats.POPULATION_LIMIT_NOT_POSITIVE, populationLimit);
073        }
074        if (chromosomes.size() > populationLimit) {
075            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
076                                                chromosomes.size(), populationLimit, false);
077        }
078        this.populationLimit = populationLimit;
079        this.chromosomes = new ArrayList<>(populationLimit);
080        this.chromosomes.addAll(chromosomes);
081    }
082
083    /**
084     * Add a {@link Collection} of chromosomes to this {@link Population}.
085     * @param chromosomeColl a {@link Collection} of chromosomes
086     * @throws NumberIsTooLargeException if the population would exceed the population limit when
087     * adding this chromosome
088     * @since 3.1
089     */
090    public void addChromosomes(final Collection<Chromosome> chromosomeColl) throws NumberIsTooLargeException {
091        if (chromosomes.size() + chromosomeColl.size() > populationLimit) {
092            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
093                                                chromosomes.size(), populationLimit, false);
094        }
095        this.chromosomes.addAll(chromosomeColl);
096    }
097
098    /**
099     * Returns an unmodifiable list of the chromosomes in this population.
100     * @return the unmodifiable list of chromosomes
101     */
102    public List<Chromosome> getChromosomes() {
103        return Collections.unmodifiableList(chromosomes);
104    }
105
106    /**
107     * Access the list of chromosomes.
108     * @return the list of chromosomes
109     * @since 3.1
110     */
111    protected List<Chromosome> getChromosomeList() {
112        return chromosomes;
113    }
114
115    /**
116     * Add the given chromosome to the population.
117     *
118     * @param chromosome the chromosome to add.
119     * @throws NumberIsTooLargeException if the population would exceed the {@code populationLimit} after
120     *   adding this chromosome
121     */
122    @Override
123    public void addChromosome(final Chromosome chromosome) throws NumberIsTooLargeException {
124        if (chromosomes.size() >= populationLimit) {
125            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
126                                                chromosomes.size(), populationLimit, false);
127        }
128        this.chromosomes.add(chromosome);
129    }
130
131    /**
132     * Access the fittest chromosome in this population.
133     * @return the fittest chromosome.
134     */
135    @Override
136    public Chromosome getFittestChromosome() {
137        // best so far
138        Chromosome bestChromosome = this.chromosomes.get(0);
139        for (Chromosome chromosome : this.chromosomes) {
140            if (chromosome.compareTo(bestChromosome) > 0) {
141                // better chromosome found
142                bestChromosome = chromosome;
143            }
144        }
145        return bestChromosome;
146    }
147
148    /**
149     * Access the maximum population size.
150     * @return the maximum population size.
151     */
152    @Override
153    public int getPopulationLimit() {
154        return this.populationLimit;
155    }
156
157    /**
158     * Sets the maximal population size.
159     * @param populationLimit maximal population size.
160     * @throws NotPositiveException if the population limit is not a positive number (&lt; 1)
161     * @throws NumberIsTooSmallException if the new population size is smaller than the current number
162     *   of chromosomes in the population
163     */
164    public void setPopulationLimit(final int populationLimit) throws NotPositiveException, NumberIsTooSmallException {
165        if (populationLimit <= 0) {
166            throw new NotPositiveException(LocalizedFormats.POPULATION_LIMIT_NOT_POSITIVE, populationLimit);
167        }
168        if (populationLimit < chromosomes.size()) {
169            throw new NumberIsTooSmallException(populationLimit, chromosomes.size(), true);
170        }
171        this.populationLimit = populationLimit;
172    }
173
174    /**
175     * Access the current population size.
176     * @return the current population size.
177     */
178    @Override
179    public int getPopulationSize() {
180        return this.chromosomes.size();
181    }
182
183    /**
184     * {@inheritDoc}
185     */
186    @Override
187    public String toString() {
188        return this.chromosomes.toString();
189    }
190
191    /**
192     * Returns an iterator over the unmodifiable list of chromosomes.
193     * <p>Any call to {@link Iterator#remove()} will result in a {@link UnsupportedOperationException}.</p>
194     *
195     * @return chromosome iterator
196     */
197    @Override
198    public Iterator<Chromosome> iterator() {
199        return getChromosomes().iterator();
200    }
201}