source: java/ecj/cecj/archive/MaxSolveArchive.java @ 107

/*
  Copyright 2009 by Marcin Szubert
  Licensed under the Academic Free License version 3.0
 */

package cecj.archive;

import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import cecj.interaction.InteractionResult;
import cecj.utils.EquivalenceComparator;

import ec.EvolutionState;
import ec.Individual;
import ec.util.Parameter;

/**
 * The simplest type of candidate-test archive.
 * 
 * During the first step of the <code>submit</code> method, new candidates and tests are added to
 * corresponding archives; then duplicate candidate solutions are eliminated (two individuals are
 * considered equal if for each test in the archive they have identical outcomes). After sorting
 * candidates by number of solved tests, the best <code>archive-size</code> individuals are kept in
 * the archive. The last step is elimination of unsolved and duplicated (with respect to the
 * outcomes against archival candidates) tests.
 * 
 * Since duplicates removal is a common task, a purpose-built <code>EquivalenceComparator</code>
 * interface is used for defining custom equivalence criteria.
 * 
 * @author Marcin Szubert
 * 
 */
public class MaxSolveArchive extends CandidateTestArchive {

        private static final String P_ARCHIVE_SIZE = "archive-size";

        private int archiveSize;

        @Override
        public void setup(EvolutionState state, Parameter base) {
                super.setup(state, base);

                Parameter archiveSizeParameter = base.push(P_ARCHIVE_SIZE);
                archiveSize = state.parameters.getInt(archiveSizeParameter, null, 1);
                if (archiveSize <= 0) {
                        state.output.fatal("Archive size must be > 0\n");
                }
        }

        @Override
        protected void submit(EvolutionState state, List<Individual> candidates,
                        List<Individual> cArchive, List<Individual> tests, List<Individual> tArchive) {
                cArchive.addAll(candidates);
                tArchive.addAll(tests);

                eliminateDuplicates(cArchive, new CandidateEquivalenceComparator(state, tArchive));
                Map<Individual, Integer> numSolved = countSolved(state, cArchive, tArchive);
                Collections.sort(cArchive, new NumberSolvedComparator(numSolved));

                if (cArchive.size() > archiveSize) {
                        cArchive.subList(archiveSize, cArchive.size()).clear();
                }

                eliminateUnsolvedTests(state, cArchive, tArchive);
                eliminateDuplicates(tArchive, new TestEquivalenceComparator(state, cArchive));
        }

        private void eliminateDuplicates(List<Individual> archive,
                        EquivalenceComparator<Individual> comparator) {
                for (int ind1 = 0; ind1 < archive.size(); ind1++) {
                        for (int ind2 = archive.size(); ind2 > ind1; ind2--) {
                                if (comparator.equal(archive.get(ind1), archive.get(ind2))) {
                                        archive.remove(ind2);
                                }
                        }
                }
        }

        private void eliminateUnsolvedTests(EvolutionState state, List<Individual> cArchive,
                        List<Individual> tArchive) {
                for (int test = 0; test < tArchive.size(); test++) {
                        if (!isSolved(state, tArchive.get(test), cArchive)) {
                                tArchive.remove(test);
                        }
                }
        }

        private boolean isSolved(EvolutionState state, Individual test, List<Individual> candidates) {
                for (Individual candidate : candidates) {
                        if (problem.solves(state, candidate, test)) {
                                return true;
                        }
                }
                return false;
        }

        private Map<Individual, Integer> countSolved(EvolutionState state, List<Individual> candidates,
                        List<Individual> tests) {
                Map<Individual, Integer> result = new HashMap<Individual, Integer>();
                for (Individual candidate : candidates) {
                        int countTest = 0;
                        for (Individual test : tests) {
                                if (problem.solves(state, candidate, test)) {
                                        countTest++;
                                }
                        }
                        result.put(candidate, countTest);
                }
                return result;
        }

        private class NumberSolvedComparator implements Comparator<Individual> {
                private Map<Individual, Integer> solved;

                public NumberSolvedComparator(Map<Individual, Integer> solved) {
                        this.solved = solved;
                }

                public int compare(Individual o1, Individual o2) {
                        if (solved.get(o1) > solved.get(o2)) {
                                return -1;
                        } else if (solved.get(o1) > solved.get(o2)) {
                                return 1;
                        } else {
                                return 0;
                        }
                }
        }

        private class CandidateEquivalenceComparator implements EquivalenceComparator<Individual> {
                private EvolutionState state;
                private List<Individual> tests;

                public CandidateEquivalenceComparator(EvolutionState state, List<Individual> tests) {
                        this.state = state;
                        this.tests = tests;
                }

                public boolean equal(Individual o1, Individual o2) {
                        for (Individual test : tests) {
                                InteractionResult result1 = problem.test(state, o1, test).first;
                                InteractionResult result2 = problem.test(state, o2, test).first;
                                if (!result1.equals(result2)) {
                                        return false;
                                }
                        }
                        return false;
                }
        }

        private class TestEquivalenceComparator implements EquivalenceComparator<Individual> {
                private EvolutionState state;
                private List<Individual> candidates;

                public TestEquivalenceComparator(EvolutionState state, List<Individual> candidates) {
                        this.state = state;
                        this.candidates = candidates;
                }

                public boolean equal(Individual o1, Individual o2) {
                        for (Individual candidate : candidates) {
                                InteractionResult result1 = problem.test(state, candidate, o2).second;
                                InteractionResult result2 = problem.test(state, candidate, o2).second;
                                if (!result1.equals(result2)) {
                                        return false;
                                }
                        }
                        return false;
                }
        }
}