001package org.cpsolver.coursett.criteria;
002
003import java.util.Collection;
004import java.util.HashSet;
005import java.util.Set;
006
007import org.cpsolver.coursett.constraint.GroupConstraint;
008import org.cpsolver.coursett.model.Lecture;
009import org.cpsolver.coursett.model.Placement;
010import org.cpsolver.coursett.model.TimetableModel;
011import org.cpsolver.ifs.assignment.Assignment;
012import org.cpsolver.ifs.util.DataProperties;
013
014
015/**
016 * Distribution preferences. This criterion counts how well the soft distribution preferences
017 * are met. This is a sum of {@link GroupConstraint#getPreference()} of all soft distribution 
018 * (group) constraints.
019 * <br>
020 * 
021 * @author  Tomáš Müller
022 * @version CourseTT 1.3 (University Course Timetabling)<br>
023 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
024 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
025 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
026 * <br>
027 *          This library is free software; you can redistribute it and/or modify
028 *          it under the terms of the GNU Lesser General Public License as
029 *          published by the Free Software Foundation; either version 3 of the
030 *          License, or (at your option) any later version. <br>
031 * <br>
032 *          This library is distributed in the hope that it will be useful, but
033 *          WITHOUT ANY WARRANTY; without even the implied warranty of
034 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
035 *          Lesser General Public License for more details. <br>
036 * <br>
037 *          You should have received a copy of the GNU Lesser General Public
038 *          License along with this library; if not see
039 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
040 */
041public class DistributionPreferences extends TimetablingCriterion {
042    
043    public DistributionPreferences() {
044        setValueUpdateType(ValueUpdateType.NoUpdate);
045    }
046    
047    @Override
048    public double getWeightDefault(DataProperties config) {
049        return config.getPropertyDouble("Comparator.ContrPreferenceWeight", 1.0);
050    }
051    
052    @Override
053    public String getPlacementSelectionWeightName() {
054        return "Placement.ConstrPreferenceWeight";
055    }
056
057
058    @Override
059    public double getValue(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
060        double ret = 0.0;
061        for (GroupConstraint gc : value.variable().groupConstraints())
062            ret += gc.getCurrentPreference(assignment, value);
063        return ret;
064    }
065    
066    @Override
067    public double getValue(Assignment<Lecture, Placement> assignment, Collection<Lecture> variables) {
068        double ret = 0;
069        Set<GroupConstraint> constraints = new HashSet<GroupConstraint>();
070        for (Lecture lect: variables) {
071            for (GroupConstraint gc: lect.groupConstraints()) {
072                if (!constraints.add(gc)) continue;
073                ret += gc.getContext(assignment).getPreference();
074            }
075        }
076        return ret;
077    }
078        
079    @Override
080    protected double[] computeBounds(Assignment<Lecture, Placement> assignment) {
081        double[] bounds = new double[] { 0.0, 0.0 };
082        for (GroupConstraint gc: ((TimetableModel)getModel()).getGroupConstraints()) {
083            if (!gc.isHard()) {
084                bounds[1] += Math.abs(gc.getPreference()) * (1 + (gc.variables().size() * (gc.variables().size() - 1)) / 2);
085            }
086        }
087        return bounds;
088    }
089    
090    @Override
091    public double[] getBounds(Assignment<Lecture, Placement> assignment, Collection<Lecture> variables) {
092        double[] bounds = new double[] { 0.0, 0.0 };
093        Set<GroupConstraint> constraints = new HashSet<GroupConstraint>();
094        for (Lecture lect: variables) {
095            for (GroupConstraint gc: lect.groupConstraints()) {
096                if (!gc.isHard() && constraints.add(gc)) {
097                    bounds[1] += Math.abs(gc.getPreference()) * (1 + (gc.variables().size() * (gc.variables().size() - 1)) / 2);
098                }
099            }
100        }
101        return bounds;
102    }
103}