    001package org.cpsolver.instructor.criteria;
    002
    003import java.util.Collection;
    004import java.util.HashSet;
    005import java.util.Set;
    006
    007import org.cpsolver.ifs.assignment.Assignment;
    008import org.cpsolver.ifs.model.Constraint;
    009import org.cpsolver.ifs.util.DataProperties;
    010import org.cpsolver.instructor.constraints.SameLinkConstraint;
    011import org.cpsolver.instructor.model.TeachingAssignment;
    012import org.cpsolver.instructor.model.TeachingRequest;
    013
    014/**
    015 * Same Link. This criterion counts how well are the soft Same Link Constraints (see {@link SameLinkConstraint}) met.
    016 *
    017 * @version IFS 1.3 (Instructor Sectioning)<br>
    018 *          Copyright (C) 2016 Tomáš Müller<br>
    019 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    020 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    021 * <br>
    022 *          This library is free software; you can redistribute it and/or modify
    023 *          it under the terms of the GNU Lesser General Public License as
    024 *          published by the Free Software Foundation; either version 3 of the
    025 *          License, or (at your option) any later version. <br>
    026 * <br>
    027 *          This library is distributed in the hope that it will be useful, but
    028 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    029 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    030 *          Lesser General Public License for more details. <br>
    031 * <br>
    032 *          You should have received a copy of the GNU Lesser General Public
    033 *          License along with this library; if not see
    034 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    035 */
    036public class SameLink extends InstructorSchedulingCriterion {
    037
    038    public SameLink() {
    039        setValueUpdateType(ValueUpdateType.NoUpdate);
    040    }
    041
    042    @Override
    043    public double getWeightDefault(DataProperties config) {
    044        return 100.0;
    045    }
    046
    047    @Override
    048    public double getValue(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, TeachingAssignment value, Set<TeachingAssignment> conflicts) {
    049        double ret = 0.0;
    050        for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : value.variable().constraints())
    051            if (c instanceof SameLinkConstraint)
    052                ret += ((SameLinkConstraint)c).getCurrentPreference(assignment, value);
    053        return ret;
    054    }
    055
    056    @Override
    057    public double getValue(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, Collection<TeachingRequest.Variable> variables) {
    058        double ret = 0;
    059        Set<Constraint<TeachingRequest.Variable, TeachingAssignment>> constraints = new HashSet<Constraint<TeachingRequest.Variable, TeachingAssignment>>();
    060        for (TeachingRequest.Variable req: variables) {
    061            for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : req.constraints()) {
    062                if (c instanceof SameLinkConstraint && constraints.add(c))
    063                    ret += ((SameLinkConstraint)c).getContext(assignment).getPreference();
    064            }
    065        }
    066        return ret;
    067    }
    068
    069    @Override
    070    protected double[] computeBounds(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment) {
    071        double[] bounds = new double[] { 0.0, 0.0 };
    072        for (Constraint<TeachingRequest.Variable, TeachingAssignment> c: getModel().constraints()) {
    073            if (c instanceof SameLinkConstraint && !c.isHard())
    074                bounds[1] += Math.abs(((SameLinkConstraint)c).getPreference()) * (c.variables().size() - 1);
    075        }
    076        return bounds;
    077    }
    078
    079    @Override
    080    public double[] getBounds(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, Collection<TeachingRequest.Variable> variables) {
    081        double[] bounds = new double[] { 0.0, 0.0 };
    082        Set<Constraint<TeachingRequest.Variable, TeachingAssignment>> constraints = new HashSet<Constraint<TeachingRequest.Variable, TeachingAssignment>>();
    083        for (TeachingRequest.Variable req: variables) {
    084            for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : req.constraints()) {
    085                if (c instanceof SameLinkConstraint && !c.isHard() && constraints.add(c))
    086                    bounds[1] += Math.abs(((SameLinkConstraint)c).getPreference()) * (c.variables().size() - 1);
    087            }
    088        }
    089        return bounds;
    090    }
    091
    092    @Override
    093    public String getAbbreviation() {
    094        return "SameLink";
    095    }
    096}