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 * @version IFS 1.3 (Iterative Forward Search)<br>
026 *          Copyright (C) 2014 Tomáš Müller<br>
027 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
028 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
029 * <br>
030 *          This library is free software; you can redistribute it and/or modify
031 *          it under the terms of the GNU Lesser General Public License as
032 *          published by the Free Software Foundation; either version 3 of the
033 *          License, or (at your option) any later version. <br>
034 * <br>
035 *          This library is distributed in the hope that it will be useful, but
036 *          WITHOUT ANY WARRANTY; without even the implied warranty of
037 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
038 *          Lesser General Public License for more details. <br>
039 * <br>
040 *          You should have received a copy of the GNU Lesser General Public
041 *          License along with this library; if not see
042 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
043 */
044public class TimeChange extends RandomMove<Lecture, Placement> {
045    
046    public TimeChange(DataProperties config) {
047        super(config);
048    }
049
050    @Override
051    public Neighbour<Lecture, Placement> selectNeighbour(Solution<Lecture, Placement> solution) {
052        TimetableModel model = (TimetableModel)solution.getModel();
053        Assignment<Lecture, Placement> assignment = solution.getAssignment();
054        int varIdx = ToolBox.random(model.variables().size());
055        for (int i = 0; i < model.variables().size(); i++) {
056            Lecture lecture = model.variables().get((i + varIdx) % model.variables().size());
057            Placement old = assignment.getValue(lecture);
058            if (old == null) continue;
059            List<TimeLocation> values = lecture.timeLocations();
060            if (values.isEmpty()) continue;
061            int valIdx = ToolBox.random(values.size());
062            for (int j = 0; j < values.size(); j++) {
063                TimeLocation time = values.get((j + valIdx) % values.size());
064                if (time.getPreference() > 50) continue;
065                
066                Placement placement = null;
067                if (lecture.getNrRooms() == 0)
068                    placement = new Placement(lecture, time, (RoomLocation) null);
069                else if (lecture.getNrRooms() == 1)
070                    placement = new Placement(lecture, time, old.getRoomLocation());
071                else
072                    placement = new Placement(lecture, time, old.getRoomLocations());
073
074                if (placement.isValid() && !model.inConflict(assignment, placement)) {
075                    SimpleNeighbour<Lecture, Placement> n = new SimpleNeighbour<Lecture, Placement>(lecture, placement);
076                    if (!iHC || n.value(assignment) <= 0) return n;
077                }
078            }
079        }
080        return null;
081    }
082    
083
084}