    001package org.cpsolver.studentsct.online;
    002
    003import java.util.Set;
    004
    005import org.apache.logging.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 * @author  Tomáš Müller
    028 * @version StudentSct 1.3 (Student Sectioning)<br>
    029 *          Copyright (C) 2014 Tomáš Müller<br>
    030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    032 * <br>
    033 *          This library is free software; you can redistribute it and/or modify
    034 *          it under the terms of the GNU Lesser General Public License as
    035 *          published by the Free Software Foundation; either version 3 of the
    036 *          License, or (at your option) any later version. <br>
    037 * <br>
    038 *          This library is distributed in the hope that it will be useful, but
    039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    041 *          Lesser General Public License for more details. <br>
    042 * <br>
    043 *          You should have received a copy of the GNU Lesser General Public
    044 *          License along with this library; if not see <a href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
    045 *
    046 */
    047public class OnlineSectioningModel extends StudentSectioningModel {
    048    private static Logger sLog = org.apache.logging.log4j.LogManager.getLogger(OnlineSectioningModel.class);
    049    private OverExpectedCriterion iOverExpectedCriterion;
    050
    051    public OnlineSectioningModel(DataProperties properties) {
    052        this(properties, null);
    053        try {
    054            @SuppressWarnings("unchecked")
    055            Class<OverExpectedCriterion> overExpectedCriterionClass = (Class<OverExpectedCriterion>)
    056                Class.forName(properties.getProperty("OverExpectedCriterion.Class", AvoidUnbalancedWhenNoExpectations.class.getName()));
    057            iOverExpectedCriterion = overExpectedCriterionClass.getConstructor(DataProperties.class).newInstance(properties);
    058        } catch (Exception e) {
    059                sLog.error("Unable to create custom over-expected criterion (" + e.getMessage() + "), using default.", e);
    060                iOverExpectedCriterion = new PercentageOverExpected(properties);
    061        }
    062    }
    063
    064    public OnlineSectioningModel(DataProperties config, OverExpectedCriterion criterion) {
    065        super(config);
    066        iOverExpectedCriterion = criterion;
    067        if (isMPP() && super.getKeepInitialAssignments()) {
    068            for (GlobalConstraint<Request, Enrollment> c: globalConstraints()) {
    069                if (c instanceof FixInitialAssignments) {
    070                    removeGlobalConstraint(c); break;
    071                }
    072            }
    073        }
    074    }
    075
    076    @Override
    077    public boolean getKeepInitialAssignments() {
    078        return false;
    079    }
    080
    081    /**
    082     * Get over-expected criterion
    083     * @return over-expected criterion
    084     */
    085    public OverExpectedCriterion getOverExpectedCriterion() { return iOverExpectedCriterion; }
    086
    087    /**
    088     * Set over-expected criterion
    089     * @param overExpectedCriterion over-expected criterion
    090     */
    091    public void setOverExpectedCriterion(OverExpectedCriterion overExpectedCriterion) { iOverExpectedCriterion = overExpectedCriterion; }
    092
    093    /**
    094     * Expectation penalty, to be minimized (computed using {@link OverExpectedCriterion#getOverExpected(Assignment, Section, Request)})
    095     * @param assignment current assignment
    096     * @param section section in question
    097     * @param request student course request
    098     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    099     */
    100    public double getOverExpected(Assignment<Request, Enrollment> assignment, Section section, Request request) {
    101        return getOverExpectedCriterion().getOverExpected(assignment, section, request);
    102    }
    103
    104    /**
    105     * Expectation penalty, to be minimized
    106     * @param assignment current assignment
    107     * @param enrollment current enrollment of the student
    108     * @param index only use enrollments 0 .. index - 1 from the assignment array
    109     * @param section section in question
    110     * @param request student course request
    111     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    112     */
    113    public double getOverExpected(Assignment<Request, Enrollment> assignment, Enrollment[] enrollment, int index, Section section, Request request) {
    114        if (getOverExpectedCriterion() instanceof OverExpectedCriterion.HasContext)
    115            return ((OverExpectedCriterion.HasContext)getOverExpectedCriterion()).getOverExpected(assignment, enrollment, index, section, request);
    116        else
    117            return getOverExpectedCriterion().getOverExpected(assignment, section, request);
    118    }
    119
    120    /**
    121     * Expectation penalty, to be minimized.
    122     * A variant of the {@link OverExpectedCriterion#getOverExpected(Assignment, Section, Request)} method that can be called from {@link Constraint#computeConflicts(Assignment, Value, Set)}.
    123     * @param assignment current assignment
    124     * @param selection selected enrollment question
    125     * @param value an enrollment to be assigned
    126     * @param conflicts enrollments that have been already identified as conflicting
    127     * @return expectation penalty (typically 1.0 / number of subparts when over-expected, 0.0 otherwise)
    128     */
    129    public double getOverExpected(Assignment<Request, Enrollment> assignment, Enrollment selection, Enrollment value, Set<Enrollment> conflicts) {
    130        if (getOverExpectedCriterion() instanceof OverExpectedCriterion.HasContext)
    131            return ((OverExpectedCriterion.HasContext)getOverExpectedCriterion()).getOverExpected(assignment, selection, value, conflicts);
    132        else {
    133            if (selection == null || !selection.isCourseRequest()) return 0.0;
    134            double penalty = 0.0;
    135            for (Section section: selection.getSections())
    136                penalty += getOverExpectedCriterion().getOverExpected(assignment, section, selection.getRequest());
    137            return penalty;
    138        }
    139    }
    140
    141}