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