001package org.cpsolver.coursett.criteria;
002
003import java.util.Collection;
004import java.util.HashSet;
005import java.util.Set;
006
007import org.cpsolver.coursett.Constants;
008import org.cpsolver.coursett.constraint.InstructorConstraint;
009import org.cpsolver.coursett.model.Lecture;
010import org.cpsolver.coursett.model.Placement;
011import org.cpsolver.coursett.model.TimetableModel;
012import org.cpsolver.ifs.assignment.Assignment;
013import org.cpsolver.ifs.util.DataProperties;
014
015
016
017/**
018 * Bact-to-back instructor preferences. This criterion counts cases when an instructor
019 * has to teach two classes in two rooms that are too far a part. This objective
020 * is counter by the {@link InstructorConstraint}
021 * (see {@link InstructorConstraint#getDistancePreference(Placement, Placement)}).
022 * <br>
023 * 
024 * @author  Tomáš Müller
025 * @version CourseTT 1.3 (University Course Timetabling)<br>
026 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
027 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
028 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
029 * <br>
030 *          This library is free software; you can redistribute it and/or modify
031 *          it under the terms of the GNU Lesser General Public License as
032 *          published by the Free Software Foundation; either version 3 of the
033 *          License, or (at your option) any later version. <br>
034 * <br>
035 *          This library is distributed in the hope that it will be useful, but
036 *          WITHOUT ANY WARRANTY; without even the implied warranty of
037 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
038 *          Lesser General Public License for more details. <br>
039 * <br>
040 *          You should have received a copy of the GNU Lesser General Public
041 *          License along with this library; if not see
042 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
043 */
044public class BackToBackInstructorPreferences extends TimetablingCriterion {
045    
046    public BackToBackInstructorPreferences() {
047        setValueUpdateType(ValueUpdateType.NoUpdate);
048    }
049    
050    @Override
051    public double getWeightDefault(DataProperties config) {
052        return Constants.sPreferenceLevelDiscouraged * config.getPropertyDouble("Comparator.DistanceInstructorPreferenceWeight", 1.0);
053    }
054    
055    @Override
056    public String getPlacementSelectionWeightName() {
057        return "Placement.DistanceInstructorPreferenceWeight";
058    }
059    
060    protected int penalty(Assignment<Lecture, Placement> assignment, Placement value) {
061        int ret = 0;
062        for (InstructorConstraint ic: value.variable().getInstructorConstraints()) {
063            ret += ic.getPreference(assignment, value);
064        }
065        return ret;
066    }
067    
068    @Override
069    public double getValue(Assignment<Lecture, Placement> assignment, Placement value, Set<Placement> conflicts) {
070        double ret = penalty(assignment, value);
071        if (conflicts != null)
072            for (Placement conflict: conflicts)
073                ret -= penalty(assignment, conflict);
074        return ret;
075    }
076
077    @Override
078    public double getValue(Assignment<Lecture, Placement> assignment, Collection<Lecture> variables) {
079        double ret = 0;
080        Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>();
081        for (Lecture lect: variables) {
082            for (InstructorConstraint ic: lect.getInstructorConstraints()) {
083                if (!constraints.add(ic)) continue;
084                ret += ic.getPreference(assignment);
085            }
086        }
087        return ret;
088    }
089    
090    @Override
091    protected double[] computeBounds(Assignment<Lecture, Placement> assignment) {
092        double[] bounds = new double[] { 0.0, 0.0 };
093        for (InstructorConstraint ic: ((TimetableModel)getModel()).getInstructorConstraints())
094            bounds[1] += ic.getWorstPreference();
095        return bounds;
096    }
097    
098    @Override
099    public double[] getBounds(Assignment<Lecture, Placement> assignment, Collection<Lecture> variables) {
100        double[] bounds = new double[] { 0.0, 0.0 };
101        Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>();
102        for (Lecture lect: variables) {
103            for (InstructorConstraint ic: lect.getInstructorConstraints()) {
104                if (!constraints.add(ic)) continue;
105                bounds[1] += ic.getWorstPreference();
106            }
107        }
108        return bounds;
109    }
110}