001package net.sf.cpsolver.coursett.neighbourhoods;
002
003import java.util.List;
004
005import net.sf.cpsolver.coursett.model.Lecture;
006import net.sf.cpsolver.coursett.model.Placement;
007import net.sf.cpsolver.coursett.model.RoomLocation;
008import net.sf.cpsolver.coursett.model.TimeLocation;
009import net.sf.cpsolver.coursett.model.TimetableModel;
010import net.sf.cpsolver.ifs.algorithms.neighbourhoods.RandomMove;
011import net.sf.cpsolver.ifs.model.Neighbour;
012import net.sf.cpsolver.ifs.model.SimpleNeighbour;
013import net.sf.cpsolver.ifs.solution.Solution;
014import net.sf.cpsolver.ifs.util.DataProperties;
015import net.sf.cpsolver.ifs.util.ToolBox;
016
017/**
018 * Try to assign a class with a new time. A class is selected randomly, a
019 * different (available) time is randomly selected for the class -- the class is
020 * assigned into the new time if there is no conflict.
021 * <br>
022 * 
023 * @version IFS 1.2 (Iterative Forward Search)<br>
024 *          Copyright (C) 2014 Tomáš Müller<br>
025 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
026 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
027 * <br>
028 *          This library is free software; you can redistribute it and/or modify
029 *          it under the terms of the GNU Lesser General Public License as
030 *          published by the Free Software Foundation; either version 3 of the
031 *          License, or (at your option) any later version. <br>
032 * <br>
033 *          This library is distributed in the hope that it will be useful, but
034 *          WITHOUT ANY WARRANTY; without even the implied warranty of
035 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
036 *          Lesser General Public License for more details. <br>
037 * <br>
038 *          You should have received a copy of the GNU Lesser General Public
039 *          License along with this library; if not see
040 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
041 */
042public class TimeChange extends RandomMove<Lecture, Placement> {
043    
044    public TimeChange(DataProperties config) {
045        super(config);
046    }
047
048    @Override
049    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
050        TimetableModel model = (TimetableModel)solution.getModel();
051        int varIdx = ToolBox.random(model.variables().size());
052        for (int i = 0; i < model.variables().size(); i++) {
053            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
054            Placement old = lecture.getAssignment();
055            if (old == null) continue;
056            List<TimeLocation> values = lecture.timeLocations();
057            if (values.isEmpty()) continue;
058            int valIdx = ToolBox.random(values.size());
059            for (int j = 0; j < values.size(); j++) {
060                TimeLocation time = values.get((j + valIdx) % values.size());
061                if (time.getPreference() > 50) continue;
062                
063                Placement placement = null;
064                if (lecture.getNrRooms() == 0)
065                    placement = new Placement(lecture, time, (RoomLocation) null);
066                else if (lecture.getNrRooms() == 1)
067                    placement = new Placement(lecture, time, old.getRoomLocation());
068                else
069                    placement = new Placement(lecture, time, old.getRoomLocations());
070
071                if (placement.isValid() && !model.inConflict(placement)) {
072                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
073                    if (!iHC || n.value() <= 0) return n;
074                }
075            }
076        }
077        return null;
078    }
079    
080
081}