    001package org.cpsolver.exam.heuristics;
    002
    003import java.text.DecimalFormat;
    004import java.util.ArrayList;
    005import java.util.Collection;
    006import java.util.List;
    007import java.util.Map;
    008
    009
    010import org.apache.logging.log4j.Logger;
    011import org.cpsolver.exam.model.Exam;
    012import org.cpsolver.exam.model.ExamPlacement;
    013import org.cpsolver.exam.neighbours.ExamRandomMove;
    014import org.cpsolver.exam.neighbours.ExamRoomMove;
    015import org.cpsolver.exam.neighbours.ExamTimeMove;
    016import org.cpsolver.ifs.assignment.Assignment;
    017import org.cpsolver.ifs.assignment.context.AssignmentContext;
    018import org.cpsolver.ifs.assignment.context.NeighbourSelectionWithContext;
    019import org.cpsolver.ifs.heuristics.NeighbourSelection;
    020import org.cpsolver.ifs.model.LazyNeighbour;
    021import org.cpsolver.ifs.model.Model;
    022import org.cpsolver.ifs.model.Neighbour;
    023import org.cpsolver.ifs.model.LazyNeighbour.LazyNeighbourAcceptanceCriterion;
    024import org.cpsolver.ifs.solution.Solution;
    025import org.cpsolver.ifs.solution.SolutionListener;
    026import org.cpsolver.ifs.solver.Solver;
    027import org.cpsolver.ifs.util.DataProperties;
    028import org.cpsolver.ifs.util.JProf;
    029import org.cpsolver.ifs.util.Progress;
    030import org.cpsolver.ifs.util.ToolBox;
    031
    032/**
    033 * Greate deluge. In each iteration, one of the following three neighbourhoods
    034 * is selected first
    035 * <ul>
    036 * <li>random move ({@link ExamRandomMove})
    037 * <li>period swap ({@link ExamTimeMove})
    038 * <li>room swap ({@link ExamRoomMove})
    039 * </ul>
    040 * , then a neighbour is generated and it is accepted if the value of the new
    041 * solution is below certain bound. This bound is initialized to the
    042 * GreatDeluge.UpperBoundRate &times; value of the best solution ever found.
    043 * After each iteration, the bound is decreased by GreatDeluge.CoolRate (new
    044 * bound equals to old bound &times; GreatDeluge.CoolRate). If the bound gets
    045 * bellow GreatDeluge.LowerBoundRate &times; value of the best solution ever
    046 * found, it is changed back to GreatDeluge.UpperBoundRate &times; value of the
    047 * best solution ever found.
    048 *
    049 * If there was no improvement found between the bounds, the new bounds are
    050 * changed to GreatDeluge.UpperBoundRate^2 and GreatDeluge.LowerBoundRate^2,
    051 * GreatDeluge.UpperBoundRate^3 and GreatDeluge.LowerBoundRate^3, etc. till
    052 * there is an improvement found. <br>
    053 * <br>
    054 *
    055 * @version ExamTT 1.3 (Examination Timetabling)<br>
    056 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
    057 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    058 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    059 * <br>
    060 *          This library is free software; you can redistribute it and/or modify
    061 *          it under the terms of the GNU Lesser General Public License as
    062 *          published by the Free Software Foundation; either version 3 of the
    063 *          License, or (at your option) any later version. <br>
    064 * <br>
    065 *          This library is distributed in the hope that it will be useful, but
    066 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    067 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    068 *          Lesser General Public License for more details. <br>
    069 * <br>
    070 *          You should have received a copy of the GNU Lesser General Public
    071 *          License along with this library; if not see
    072 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    073 */
    074@Deprecated
    075public class ExamGreatDeluge extends NeighbourSelectionWithContext<Exam, ExamPlacement, ExamGreatDeluge.Context> implements SolutionListener<Exam, ExamPlacement>, LazyNeighbourAcceptanceCriterion<Exam, ExamPlacement> {
    076    private static Logger sLog = org.apache.logging.log4j.LogManager.getLogger(ExamGreatDeluge.class);
    077    private static DecimalFormat sDF2 = new DecimalFormat("0.00");
    078    private static DecimalFormat sDF5 = new DecimalFormat("0.00000");
    079    private double iCoolRate = 0.99999995;
    080    private double iUpperBoundRate = 1.05;
    081    private double iLowerBoundRate = 0.95;
    082    private Progress iProgress = null;
    083
    084    private List<NeighbourSelection<Exam, ExamPlacement>> iNeighbours = null;
    085
    086    /**
    087     * Constructor. Following problem properties are considered:
    088     * <ul>
    089     * <li>GreatDeluge.CoolRate ... bound cooling rate (default 0.99999995)
    090     * <li>GreatDeluge.UpperBoundRate ... bound upper bound relative to best
    091     * solution ever found (default 1.05)
    092     * <li>GreatDeluge.LowerBoundRate ... bound lower bound relative to best
    093     * solution ever found (default 0.95)
    094     * </ul>
    095     *
    096     * @param properties
    097     *            problem properties
    098     */
    099    @SuppressWarnings("unchecked")
    100    public ExamGreatDeluge(DataProperties properties) {
    101        iCoolRate = properties.getPropertyDouble("GreatDeluge.CoolRate", iCoolRate);
    102        iUpperBoundRate = properties.getPropertyDouble("GreatDeluge.UpperBoundRate", iUpperBoundRate);
    103        iLowerBoundRate = properties.getPropertyDouble("GreatDeluge.LowerBoundRate", iLowerBoundRate);
    104        String neighbours = properties.getProperty("GreatDeluge.Neighbours",
    105                ExamRandomMove.class.getName() + ";" +
    106                ExamRoomMove.class.getName() + ";" +
    107                ExamTimeMove.class.getName());
    108        neighbours += ";" + properties.getProperty("GreatDeluge.AdditionalNeighbours", "");
    109        iNeighbours = new ArrayList<NeighbourSelection<Exam,ExamPlacement>>();
    110        for (String neighbour: neighbours.split("\\;")) {
    111            if (neighbour == null || neighbour.isEmpty()) continue;
    112            try {
    113                Class<NeighbourSelection<Exam, ExamPlacement>> clazz = (Class<NeighbourSelection<Exam, ExamPlacement>>)Class.forName(neighbour);
    114                iNeighbours.add(clazz.getConstructor(DataProperties.class).newInstance(properties));
    115            } catch (Exception e) {
    116                sLog.error("Unable to use " + neighbour + ": " + e.getMessage());
    117            }
    118        }
    119    }
    120
    121    /** Initialization */
    122    @Override
    123    public void init(Solver<Exam, ExamPlacement> solver) {
    124        super.init(solver);
    125        solver.currentSolution().addSolutionListener(this);
    126        for (NeighbourSelection<Exam, ExamPlacement> neighbour: iNeighbours)
    127            neighbour.init(solver);
    128        solver.setUpdateProgress(false);
    129        iProgress = Progress.getInstance(solver.currentSolution().getModel());
    130        getContext(solver.currentSolution().getAssignment()).reset();
    131    }
    132
    133    /** Print some information
    134     * @param solution current solution
    135     **/
    136    protected void info(Solution<Exam, ExamPlacement> solution) {
    137        Assignment<Exam, ExamPlacement> assignment = solution.getAssignment();
    138        getContext(assignment).info(solution);
    139    }
    140
    141    /**
    142     * Generate neighbour -- select neighbourhood randomly, select neighbour
    143     * @param solution current solution
    144     * @return a neigbour that was selected
    145     */
    146    public Neighbour<Exam, ExamPlacement> genMove(Solution<Exam, ExamPlacement> solution) {
    147        while (true) {
    148            incIter(solution);
    149            NeighbourSelection<Exam, ExamPlacement> ns = iNeighbours.get(ToolBox.random(iNeighbours.size()));
    150            Neighbour<Exam, ExamPlacement> n = ns.selectNeighbour(solution);
    151            if (n != null)
    152                return n;
    153        }
    154    }
    155
    156    /** Accept neighbour
    157     * @param solution current solution
    158     * @param neighbour a neighbour in question
    159     * @return true if the neighbour should be accepted
    160     **/
    161    protected boolean accept(Solution<Exam, ExamPlacement> solution, Neighbour<Exam, ExamPlacement> neighbour) {
    162        if (neighbour instanceof LazyNeighbour) {
    163            ((LazyNeighbour<Exam, ExamPlacement>)neighbour).setAcceptanceCriterion(this);
    164            return true;
    165        }
    166        Assignment<Exam, ExamPlacement> assignment = solution.getAssignment();
    167        return (neighbour.value(assignment) <= 0 || solution.getModel().getTotalValue(assignment) + neighbour.value(assignment) <= getContext(assignment).getBound());
    168    }
    169
    170    /** Accept lazy neighbour */
    171    @Override
    172    public boolean accept(Assignment<Exam, ExamPlacement> assignment, LazyNeighbour<Exam, ExamPlacement> neighbour, double value) {
    173        return (value <= 0.0 || neighbour.getModel().getTotalValue(assignment) <= getContext(assignment).getBound());
    174    }
    175
    176    /** Increment iteration count, update bound
    177     * @param solution current solution
    178     **/
    179    protected void incIter(Solution<Exam, ExamPlacement> solution) {
    180        getContext(solution.getAssignment()).incIter(solution);
    181    }
    182
    183    /**
    184     * A neighbour is generated randomly untill an acceptable one is found.
    185     */
    186    @Override
    187    public Neighbour<Exam, ExamPlacement> selectNeighbour(Solution<Exam, ExamPlacement> solution) {
    188        Neighbour<Exam, ExamPlacement> neighbour = null;
    189        while ((neighbour = genMove(solution)) != null) {
    190            getContext(solution.getAssignment()).incMoves();
    191            if (accept(solution, neighbour)) {
    192                getContext(solution.getAssignment()).incAcceptedMoves();
    193                break;
    194            }
    195        }
    196        return (neighbour == null ? null : neighbour);
    197    }
    198
    199    /** Update last improving iteration count */
    200    @Override
    201    public void bestSaved(Solution<Exam, ExamPlacement> solution) {
    202        getContext(solution.getAssignment()).bestSaved(solution.getModel());
    203    }
    204
    205    @Override
    206    public void solutionUpdated(Solution<Exam, ExamPlacement> solution) {
    207    }
    208
    209    @Override
    210    public void getInfo(Solution<Exam, ExamPlacement> solution, Map<String, String> info) {
    211    }
    212
    213    @Override
    214    public void getInfo(Solution<Exam, ExamPlacement> solution, Map<String, String> info, Collection<Exam> variables) {
    215    }
    216
    217    @Override
    218    public void bestCleared(Solution<Exam, ExamPlacement> solution) {
    219    }
    220
    221    @Override
    222    public void bestRestored(Solution<Exam, ExamPlacement> solution) {
    223    }
    224
    225    @Override
    226    public Context createAssignmentContext(Assignment<Exam, ExamPlacement> assignment) {
    227        return new Context();
    228    }
    229
    230    public class Context implements AssignmentContext {
    231        private double iUpperBound;
    232        private int iMoves = 0;
    233        private int iAcceptedMoves = 0;
    234        private int iNrIdle = 0;
    235        private long iT0 = -1;
    236        private long iIter = -1;
    237        private double iBound = 0.0;
    238        private long iLastImprovingIter = 0;
    239        private double iBestValue = 0;
    240
    241        protected void reset() {
    242            iIter = -1;
    243        }
    244
    245        protected void incIter(Solution<Exam, ExamPlacement> solution) {
    246            double best = solution.getModel().getBestValue();
    247            if (iIter < 0) {
    248                iIter = 0;
    249                iLastImprovingIter = 0;
    250                iT0 = JProf.currentTimeMillis();
    251                iBound = (best > 0.0 ? iUpperBoundRate * best : best / iUpperBoundRate);
    252                iUpperBound = iBound;
    253                iNrIdle = 0;
    254                solution.restoreBest();
    255                iProgress.setPhase("Great deluge [" + (1 + iNrIdle) + "]...");
    256            } else {
    257                iIter++;
    258                if (best >= 0.0)
    259                    iBound *= iCoolRate;
    260                else
    261                    iBound /= iCoolRate;
    262            }
    263            if (iIter % 1000 == 0 && iBound > (best > 0.0 ? iUpperBoundRate * best : best / iUpperBoundRate)) {
    264                // some other thread lowered the upper bound over my bound -> adjust my bound
    265                iBound = (best > 0.0 ? iUpperBoundRate * best : best / iUpperBoundRate);
    266            }
    267            if (iIter % 100000 == 0) {
    268                info(solution);
    269            }
    270            double lowerBound = (best >= 0.0 ? Math.pow(iLowerBoundRate, 1 + iNrIdle) * best : best / Math.pow(iLowerBoundRate, 1 + iNrIdle));
    271            if (iBound < lowerBound) {
    272                iNrIdle++;
    273                sLog.info(" -<[" + iNrIdle + "]>- ");
    274                iBound = Math.max(best + 2.0, (best >= 0.0 ? Math.pow(iUpperBoundRate, iNrIdle) * best : best / Math.pow(iUpperBoundRate, iNrIdle)));
    275                iUpperBound = iBound;
    276                iProgress.setPhase("Great deluge [" + (1 + iNrIdle) + "]...");
    277                solution.restoreBest();
    278            }
    279            iProgress.setProgress(100 - Math.round(100.0 * (iBound - lowerBound) / (iUpperBound - lowerBound)));
    280        }
    281
    282        protected void info(Solution<Exam, ExamPlacement> solution) {
    283            sLog.info("Iter=" + iIter / 1000 + "k, NonImpIter=" + sDF2.format((iIter - iLastImprovingIter) / 1000.0)
    284                    + "k, Speed=" + sDF2.format(1000.0 * iIter / (JProf.currentTimeMillis() - iT0)) + " it/s");
    285            sLog.info("Bound is " + sDF2.format(iBound) + ", " + "best value is " + sDF2.format(solution.getModel().getBestValue())
    286                    + " (" + sDF2.format(100.0 * iBound / solution.getModel().getBestValue()) + "%), " + "current value is "
    287                    + sDF2.format(solution.getModel().getTotalValue(solution.getAssignment())) + " ("
    288                    + sDF2.format(100.0 * iBound / solution.getModel().getTotalValue(solution.getAssignment())) + "%), " + "#idle=" + iNrIdle
    289                    + ", " + "Pacc=" + sDF5.format(100.0 * iAcceptedMoves / iMoves) + "%");
    290            iAcceptedMoves = iMoves = 0;
    291        }
    292
    293        protected void bestSaved(Model<Exam, ExamPlacement> model) {
    294            if (Math.abs(iBestValue - model.getBestValue()) >= 1.0) {
    295                iLastImprovingIter = iIter;
    296                iNrIdle = 0;
    297                iBestValue = model.getBestValue();
    298            }
    299        }
    300
    301        public double getBound() { return iBound; }
    302
    303        public void incMoves() { iMoves ++; }
    304
    305        public void incAcceptedMoves() { iAcceptedMoves ++; }
    306    }
    307}