    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 * @author  Tomáš Müller
    018 * @version IFS 1.3 (Instructor Sectioning)<br>
    019 *          Copyright (C) 2016 Tomáš Müller<br>
    020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    022 * <br>
    023 *          This library is free software; you can redistribute it and/or modify
    024 *          it under the terms of the GNU Lesser General Public License as
    025 *          published by the Free Software Foundation; either version 3 of the
    026 *          License, or (at your option) any later version. <br>
    027 * <br>
    028 *          This library is distributed in the hope that it will be useful, but
    029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    031 *          Lesser General Public License for more details. <br>
    032 * <br>
    033 *          You should have received a copy of the GNU Lesser General Public
    034 *          License along with this library; if not see
    035 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    036 */
    037public class SameLink extends InstructorSchedulingCriterion {
    038
    039    public SameLink() {
    040        setValueUpdateType(ValueUpdateType.NoUpdate);
    041    }
    042
    043    @Override
    044    public double getWeightDefault(DataProperties config) {
    045        return 100.0;
    046    }
    047
    048    @Override
    049    public double getValue(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, TeachingAssignment value, Set<TeachingAssignment> conflicts) {
    050        double ret = 0.0;
    051        for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : value.variable().constraints())
    052            if (c instanceof SameLinkConstraint)
    053                ret += ((SameLinkConstraint)c).getCurrentPreference(assignment, value);
    054        return ret;
    055    }
    056
    057    @Override
    058    public double getValue(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, Collection<TeachingRequest.Variable> variables) {
    059        double ret = 0;
    060        Set<Constraint<TeachingRequest.Variable, TeachingAssignment>> constraints = new HashSet<Constraint<TeachingRequest.Variable, TeachingAssignment>>();
    061        for (TeachingRequest.Variable req: variables) {
    062            for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : req.constraints()) {
    063                if (c instanceof SameLinkConstraint && constraints.add(c))
    064                    ret += ((SameLinkConstraint)c).getContext(assignment).getPreference();
    065            }
    066        }
    067        return ret;
    068    }
    069
    070    @Override
    071    protected double[] computeBounds(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment) {
    072        double[] bounds = new double[] { 0.0, 0.0 };
    073        for (Constraint<TeachingRequest.Variable, TeachingAssignment> c: getModel().constraints()) {
    074            if (c instanceof SameLinkConstraint && !c.isHard())
    075                bounds[1] += Math.abs(((SameLinkConstraint)c).getPreference()) * (c.variables().size() - 1);
    076        }
    077        return bounds;
    078    }
    079
    080    @Override
    081    public double[] getBounds(Assignment<TeachingRequest.Variable, TeachingAssignment> assignment, Collection<TeachingRequest.Variable> variables) {
    082        double[] bounds = new double[] { 0.0, 0.0 };
    083        Set<Constraint<TeachingRequest.Variable, TeachingAssignment>> constraints = new HashSet<Constraint<TeachingRequest.Variable, TeachingAssignment>>();
    084        for (TeachingRequest.Variable req: variables) {
    085            for (Constraint<TeachingRequest.Variable, TeachingAssignment> c : req.constraints()) {
    086                if (c instanceof SameLinkConstraint && !c.isHard() && constraints.add(c))
    087                    bounds[1] += Math.abs(((SameLinkConstraint)c).getPreference()) * (c.variables().size() - 1);
    088            }
    089        }
    090        return bounds;
    091    }
    092
    093    @Override
    094    public String getAbbreviation() {
    095        return "SameLink";
    096    }
    097}