    001package org.cpsolver.studentsct.online;
    002
    003import java.util.Set;
    004
    005import org.apache.log4j.Logger;
    006import org.cpsolver.ifs.assignment.Assignment;
    007import org.cpsolver.ifs.model.Constraint;
    008import org.cpsolver.ifs.model.GlobalConstraint;
    009import org.cpsolver.ifs.model.Value;
    010import org.cpsolver.ifs.util.DataProperties;
    011import org.cpsolver.studentsct.StudentSectioningModel;
    012import org.cpsolver.studentsct.constraint.FixInitialAssignments;
    013import org.cpsolver.studentsct.model.Enrollment;
    014import org.cpsolver.studentsct.model.Request;
    015import org.cpsolver.studentsct.model.Section;
    016import org.cpsolver.studentsct.online.expectations.AvoidUnbalancedWhenNoExpectations;
    017import org.cpsolver.studentsct.online.expectations.OverExpectedCriterion;
    018import org.cpsolver.studentsct.online.expectations.PercentageOverExpected;
    019
    020/**
    021 * An online model. A simple extension of the {@link OnlineSectioningModel} class that allows to set the over-expected
    022 * criterion (see {@link OverExpectedCriterion}). This class is particularly useful in passing the over-expected criterion to the
    023 * online sectioning algorithms and heuristics.<br><br>
    024 * The over-expected criterion can be passed as a constructor parameter, or given using the OverExpectedCriterion.Class parameter.
    025 * It defaults to {@link AvoidUnbalancedWhenNoExpectations}.
    026 *
    027 * @version StudentSct 1.3 (Student Sectioning)<br>
    028 *          Copyright (C) 2014 Tomáš Müller<br>
    029 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    030 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    031 * <br>
    032 *          This library is free software; you can redistribute it and/or modify
    033 *          it under the terms of the GNU Lesser General Public License as
    034 *          published by the Free Software Foundation; either version 3 of the
    035 *          License, or (at your option) any later version. <br>
    036 * <br>
    037 *          This library is distributed in the hope that it will be useful, but
    038 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    039 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    040 *          Lesser General Public License for more details. <br>
    041 * <br>
    042 *          You should have received a copy of the GNU Lesser General Public
    043 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    044 *
    045 */
    046public class OnlineSectioningModel extends StudentSectioningModel {
    047    private static Logger sLog = Logger.getLogger(OnlineSectioningModel.class);
    048    private OverExpectedCriterion iOverExpectedCriterion;
    049
    050    public OnlineSectioningModel(DataProperties properties) {
    051        this(properties, null);
    052        try {
    053            @SuppressWarnings("unchecked")
    054            Class<OverExpectedCriterion> overExpectedCriterionClass = (Class<OverExpectedCriterion>)
    055                Class.forName(properties.getProperty("OverExpectedCriterion.Class", AvoidUnbalancedWhenNoExpectations.class.getName()));
    056            iOverExpectedCriterion = overExpectedCriterionClass.getConstructor(DataProperties.class).newInstance(properties);
    057        } catch (Exception e) {
    058                sLog.error("Unable to create custom over-expected criterion (" + e.getMessage() + "), using default.", e);
    059                iOverExpectedCriterion = new PercentageOverExpected(properties);
    060        }
    061    }
    062
    063    public OnlineSectioningModel(DataProperties config, OverExpectedCriterion criterion) {
    064        super(config);
    065        iOverExpectedCriterion = criterion;
    066        if (isMPP() && super.getKeepInitialAssignments()) {
    067            for (GlobalConstraint<Request, Enrollment> c: globalConstraints()) {
    068                if (c instanceof FixInitialAssignments) {
    069                    removeGlobalConstraint(c); break;
    070                }
    071            }
    072        }
    073    }
    074
    075    @Override
    076    public boolean getKeepInitialAssignments() {
    077        return false;
    078    }
    079
    080    /**
    081     * Get over-expected criterion
    082     * @return over-expected criterion
    083     */
    084    public OverExpectedCriterion getOverExpectedCriterion() { return iOverExpectedCriterion; }
    085
    086    /**
    087     * Set over-expected criterion
    088     * @param overExpectedCriterion over-expected criterion
    089     */
    090    public void setOverExpectedCriterion(OverExpectedCriterion overExpectedCriterion) { iOverExpectedCriterion = overExpectedCriterion; }
    091
    092    /**
    093     * Expectation penalty, to be minimized (computed using {@link OverExpectedCriterion#getOverExpected(Assignment, Section, Request)})
    094     * @param assignment current assignment
    095     * @param section section in question
    096     * @param request student course request
    097     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    098     */
    099    public double getOverExpected(Assignment<Request, Enrollment> assignment, Section section, Request request) {
    100        return getOverExpectedCriterion().getOverExpected(assignment, section, request);
    101    }
    102
    103    /**
    104     * Expectation penalty, to be minimized
    105     * @param assignment current assignment
    106     * @param enrollment current enrollment of the student
    107     * @param index only use enrollments 0 .. index - 1 from the assignment array
    108     * @param section section in question
    109     * @param request student course request
    110     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    111     */
    112    public double getOverExpected(Assignment<Request, Enrollment> assignment, Enrollment[] enrollment, int index, Section section, Request request) {
    113        if (getOverExpectedCriterion() instanceof OverExpectedCriterion.HasContext)
    114            return ((OverExpectedCriterion.HasContext)getOverExpectedCriterion()).getOverExpected(assignment, enrollment, index, section, request);
    115        else
    116            return getOverExpectedCriterion().getOverExpected(assignment, section, request);
    117    }
    118
    119    /**
    120     * Expectation penalty, to be minimized.
    121     * A variant of the {@link OverExpectedCriterion#getOverExpected(Assignment, Section, Request)} method that can be called from {@link Constraint#computeConflicts(Assignment, Value, Set)}.
    122     * @param assignment current assignment
    123     * @param selection selected enrollment question
    124     * @param value an enrollment to be assigned
    125     * @param conflicts enrollments that have been already identified as conflicting
    126     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    127     */
    128    public double getOverExpected(Assignment<Request, Enrollment> assignment, Enrollment selection, Enrollment value, Set<Enrollment> conflicts) {
    129        if (getOverExpectedCriterion() instanceof OverExpectedCriterion.HasContext)
    130            return ((OverExpectedCriterion.HasContext)getOverExpectedCriterion()).getOverExpected(assignment, selection, value, conflicts);
    131        else {
    132            if (selection == null || !selection.isCourseRequest()) return 0.0;
    133            double penalty = 0.0;
    134            for (Section section: selection.getSections())
    135                penalty += getOverExpectedCriterion().getOverExpected(assignment, section, selection.getRequest());
    136            return penalty;
    137        }
    138    }
    139
    140}