    001package net.sf.cpsolver.coursett.criteria;
    002
    003import java.util.Collection;
    004import java.util.HashSet;
    005import java.util.Set;
    006
    007import net.sf.cpsolver.coursett.Constants;
    008import net.sf.cpsolver.coursett.constraint.InstructorConstraint;
    009import net.sf.cpsolver.coursett.model.Lecture;
    010import net.sf.cpsolver.coursett.model.Placement;
    011import net.sf.cpsolver.coursett.model.TimetableModel;
    012
    013import net.sf.cpsolver.ifs.util.DataProperties;
    014
    015/**
    016 * Bact-to-back instructor preferences. This criterion counts cases when an instructor
    017 * has to teach two classes in two rooms that are too far a part. This objective
    018 * is counter by the {@link InstructorConstraint}
    019 * (see {@link InstructorConstraint#getDistancePreference(Placement, Placement)}).
    020 * <br>
    021 *
    022 * @version CourseTT 1.2 (University Course Timetabling)<br>
    023 *          Copyright (C) 2006 - 2011 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 BackToBackInstructorPreferences extends TimetablingCriterion {
    042
    043    public BackToBackInstructorPreferences() {
    044        iValueUpdateType = ValueUpdateType.NoUpdate;
    045    }
    046
    047    @Override
    048    public double getWeightDefault(DataProperties config) {
    049        return Constants.sPreferenceLevelDiscouraged * config.getPropertyDouble("Comparator.DistanceInstructorPreferenceWeight", 1.0);
    050    }
    051
    052    @Override
    053    public String getPlacementSelectionWeightName() {
    054        return "Placement.DistanceInstructorPreferenceWeight";
    055    }
    056
    057    protected int penalty(Placement value) {
    058        int ret = 0;
    059        for (InstructorConstraint ic: value.variable().getInstructorConstraints()) {
    060            ret += ic.getPreference(value);
    061        }
    062        return ret;
    063    }
    064
    065    @Override
    066    public double getValue(Placement value, Set<Placement> conflicts) {
    067        double ret = penalty(value);
    068        if (conflicts != null)
    069            for (Placement conflict: conflicts)
    070                ret -= penalty(conflict);
    071        return ret;
    072    }
    073
    074    @Override
    075    public double getValue(Collection<Lecture> variables) {
    076        double ret = 0;
    077        Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>();
    078        for (Lecture lect: variables) {
    079            for (InstructorConstraint ic: lect.getInstructorConstraints()) {
    080                if (!constraints.add(ic)) continue;
    081                ret += ic.getPreference();
    082            }
    083        }
    084        return ret;
    085    }
    086
    087    @Override
    088    protected double[] computeBounds() {
    089        double[] bounds = new double[] { 0.0, 0.0 };
    090        for (InstructorConstraint ic: ((TimetableModel)getModel()).getInstructorConstraints())
    091            bounds[1] += ic.getWorstPreference();
    092        return bounds;
    093    }
    094
    095    @Override
    096    public double[] getBounds(Collection<Lecture> variables) {
    097        double[] bounds = new double[] { 0.0, 0.0 };
    098        Set<InstructorConstraint> constraints = new HashSet<InstructorConstraint>();
    099        for (Lecture lect: variables) {
    100            for (InstructorConstraint ic: lect.getInstructorConstraints()) {
    101                if (!constraints.add(ic)) continue;
    102                bounds[1] += ic.getWorstPreference();
    103            }
    104        }
    105        return bounds;
    106    }
    107}