001package net.sf.cpsolver.coursett.criteria.placement;
002
003import java.util.Set;
004
005import net.sf.cpsolver.coursett.model.Lecture;
006import net.sf.cpsolver.coursett.model.Placement;
007import net.sf.cpsolver.ifs.solver.Solver;
008
009/**
010 * Difference between proposed and best time assignment. Time assignments
011 * that are do not maximize time preference are penalized by the difference
012 * in the preference.
013 * <br>
014 * 
015 * @version CourseTT 1.2 (University Course Timetabling)<br>
016 *          Copyright (C) 2006 - 2011 Tomáš Müller<br>
017 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
018 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
019 * <br>
020 *          This library is free software; you can redistribute it and/or modify
021 *          it under the terms of the GNU Lesser General Public License as
022 *          published by the Free Software Foundation; either version 3 of the
023 *          License, or (at your option) any later version. <br>
024 * <br>
025 *          This library is distributed in the hope that it will be useful, but
026 *          WITHOUT ANY WARRANTY; without even the implied warranty of
027 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
028 *          Lesser General Public License for more details. <br>
029 * <br>
030 *          You should have received a copy of the GNU Lesser General Public
031 *          License along with this library; if not see
032 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
033 */
034public class DeltaTimePreference extends PlacementSelectionCriterion {
035    private double iLevel1DefaultWeight = 0.0;
036    
037    @Override
038    public boolean init(Solver<Lecture, Placement> solver) {
039        iLevel1DefaultWeight = solver.getProperties().getPropertyDouble("Comparator.TimePreferenceWeight", 1.0) / 2.0;
040        return super.init(solver);
041    }
042
043    @Override
044    public String getPlacementSelectionWeightName() {
045        return "Placement.DeltaTimePreferenceWeight";
046    }
047
048    @Override
049    public double getValue(Placement value, Set<Placement> conflicts) {
050        double ret = value.variable().getWeight() * (value.getTimeLocation().getNormalizedPreference() - value.variable().getBestTimePreference());
051        if (conflicts != null)
052            for (Placement placement : conflicts) {
053                double timePref = placement.getTimeLocation().getNormalizedPreference();
054                ret -= placement.variable().getWeight() * (timePref - placement.variable().getBestTimePreference());
055            }
056        return ret;
057    }
058
059    @Override
060    public double getPlacementSelectionWeightDefault(int level) {
061        return (level == 0 ? iLevel1DefaultWeight : 0.0);
062    }
063}