001    package net.sf.cpsolver.coursett.criteria.placement;
002    
003    import java.util.Set;
004    
005    import net.sf.cpsolver.coursett.model.Lecture;
006    import net.sf.cpsolver.coursett.model.Placement;
007    import 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 Tomas Muller<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     */
034    public 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.getTimeLocation().getNormalizedPreference() - value.variable().getBestTimePreference();
051            if (conflicts != null)
052                for (Placement placement : conflicts) {
053                    double timePref = placement.getTimeLocation().getNormalizedPreference();
054                    ret -= 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    }