    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}