    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}