001package org.cpsolver.coursett.neighbourhoods;
002
003import java.util.List;
004
005import org.cpsolver.coursett.model.Lecture;
006import org.cpsolver.coursett.model.Placement;
007import org.cpsolver.coursett.model.RoomLocation;
008import org.cpsolver.coursett.model.TimeLocation;
009import org.cpsolver.coursett.model.TimetableModel;
010import org.cpsolver.ifs.algorithms.neighbourhoods.RandomMove;
011import org.cpsolver.ifs.assignment.Assignment;
012import org.cpsolver.ifs.model.Neighbour;
013import org.cpsolver.ifs.model.SimpleNeighbour;
014import org.cpsolver.ifs.solution.Solution;
015import org.cpsolver.ifs.util.DataProperties;
016import org.cpsolver.ifs.util.ToolBox;
017
018
019/**
020 * Try to assign a class with a new time. A class is selected randomly, a
021 * different (available) time is randomly selected for the class -- the class is
022 * assigned into the new time if there is no conflict.
023 * <br>
024 * 
025 * @author  Tomáš Müller
026 * @version IFS 1.3 (Iterative Forward Search)<br>
027 *          Copyright (C) 2014 Tomáš Müller<br>
028 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
029 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
030 * <br>
031 *          This library is free software; you can redistribute it and/or modify
032 *          it under the terms of the GNU Lesser General Public License as
033 *          published by the Free Software Foundation; either version 3 of the
034 *          License, or (at your option) any later version. <br>
035 * <br>
036 *          This library is distributed in the hope that it will be useful, but
037 *          WITHOUT ANY WARRANTY; without even the implied warranty of
038 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
039 *          Lesser General Public License for more details. <br>
040 * <br>
041 *          You should have received a copy of the GNU Lesser General Public
042 *          License along with this library; if not see
043 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
044 */
045public class TimeChange extends RandomMove<Lecture, Placement> {
046    
047    public TimeChange(DataProperties config) {
048        super(config);
049    }
050
051    @Override
052    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
053        TimetableModel model = (TimetableModel)solution.getModel();
054        Assignment<Lecture, Placement> assignment = solution.getAssignment();
055        int varIdx = ToolBox.random(model.variables().size());
056        for (int i = 0; i < model.variables().size(); i++) {
057            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
058            Placement old = assignment.getValue(lecture);
059            if (old == null) continue;
060            List<TimeLocation> values = lecture.timeLocations();
061            if (values.isEmpty()) continue;
062            int valIdx = ToolBox.random(values.size());
063            for (int j = 0; j < values.size(); j++) {
064                TimeLocation time = values.get((j + valIdx) % values.size());
065                if (time.getPreference() > 50) continue;
066                
067                Placement placement = null;
068                if (lecture.getNrRooms() == 0)
069                    placement = new Placement(lecture, time, (RoomLocation) null);
070                else if (lecture.getNrRooms() == 1)
071                    placement = new Placement(lecture, time, old.getRoomLocation());
072                else
073                    placement = new Placement(lecture, time, old.getRoomLocations());
074
075                if (placement.isValid() && !model.inConflict(assignment, placement)) {
076                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
077                    if (!iHC || n.value(assignment) <= 0) return n;
078                }
079            }
080        }
081        return null;
082    }
083    
084
085}