001package org.cpsolver.coursett.criteria;
002
003import java.util.Collection;
004import java.util.Set;
005
006import org.cpsolver.coursett.model.Lecture;
007import org.cpsolver.coursett.model.Placement;
008import org.cpsolver.coursett.model.TimeLocation;
009import org.cpsolver.ifs.assignment.Assignment;
010import org.cpsolver.ifs.util.DataProperties;
011
012
013/**
014 * Time preferences. This criterion counts how well the time preferences are met. This is
015 * a sum of {@link TimeLocation#getNormalizedPreference()} of the assigned classes.
016 * <br>
017 * 
018 * @author  Tomáš Müller
019 * @version CourseTT 1.3 (University Course Timetabling)<br>
020 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
021 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
022 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
023 * <br>
024 *          This library is free software; you can redistribute it and/or modify
025 *          it under the terms of the GNU Lesser General Public License as
026 *          published by the Free Software Foundation; either version 3 of the
027 *          License, or (at your option) any later version. <br>
028 * <br>
029 *          This library is distributed in the hope that it will be useful, but
030 *          WITHOUT ANY WARRANTY; without even the implied warranty of
031 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
032 *          Lesser General Public License for more details. <br>
033 * <br>
034 *          You should have received a copy of the GNU Lesser General Public
035 *          License along with this library; if not see
036 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
037 */
038public class TimePreferences extends TimetablingCriterion {
039
040    @Override
041    public double getWeightDefault(DataProperties config) {
042        return config.getPropertyDouble("Comparator.TimePreferenceWeight", 1.0);
043    }
044
045    @Override
046    public String getPlacementSelectionWeightName() {
047        return "Placement.TimePreferenceWeight";
048    }
049    
050    private double preference(Placement value) {
051        return value.getTimePenalty();
052    }
053
054    @Override
055    public double getValue(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
056        if (value.variable().isCommitted()) return 0.0;
057        double ret = value.variable().getWeight() * preference(value);
058        if (conflicts != null)
059            for (Placement conflict: conflicts)
060                ret -= conflict.variable().getWeight() * preference(conflict);
061        return ret;
062    }
063        
064    @Override
065    public double[] getBounds(Assignment<Lecture, Placement> assignment, Collection<Lecture> variables) {
066        double[] bounds = new double[] { 0.0, 0.0 };
067        for (Lecture lect: variables) {
068            if (lect.isCommitted()) continue;
069            double[] p = lect.getMinMaxTimePreference();
070            bounds[1] += lect.getWeight() * (p[1] - p[0]);
071        }
072        return bounds;
073    }
074
075}