    001package org.cpsolver.studentsct.heuristics.studentord;
    002
    003import org.cpsolver.ifs.util.DataProperties;
    004import org.cpsolver.studentsct.model.CourseRequest;
    005import org.cpsolver.studentsct.model.Request;
    006import org.cpsolver.studentsct.model.Student;
    007
    008/**
    009 * Return the given set of students in an order of average number of request groups of
    010 * each student. If two students are involved in the same number of groups, the comparison
    011 * falls down to the average number of choices of each student (students with less choices first).
    012 * <br>
    013 *
    014 * @author  Tomáš Müller
    015 * @version StudentSct 1.3 (Student Sectioning)<br>
    016 *          Copyright (C) 2015 Tomáš Müller<br>
    017 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    018 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    019 * <br>
    020 *          This library is free software; you can redistribute it and/or modify
    021 *          it under the terms of the GNU Lesser General Public License as
    022 *          published by the Free Software Foundation; either version 3 of the
    023 *          License, or (at your option) any later version. <br>
    024 * <br>
    025 *          This library is distributed in the hope that it will be useful, but
    026 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    027 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    028 *          Lesser General Public License for more details. <br>
    029 * <br>
    030 *          You should have received a copy of the GNU Lesser General Public
    031 *          License along with this library; if not see
    032 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    033 */
    034public class StudentGroupsChoiceRealFirstOrder extends StudentChoiceOrder {
    035
    036    public StudentGroupsChoiceRealFirstOrder(DataProperties config) {
    037        super(config);
    038    }
    039
    040    public StudentGroupsChoiceRealFirstOrder() {
    041        super(new DataProperties());
    042        setReverse(true);
    043    }
    044
    045    @Override
    046    public int compare(Student s1, Student s2) {
    047        if (s1.getPriority() != s2.getPriority()) return (s1.getPriority().ordinal() < s2.getPriority().ordinal() ? -1 : 1);
    048        if (s1.isDummy()) {
    049            if (!s2.isDummy())
    050                return 1;
    051        } else if (s2.isDummy())
    052            return -1;
    053
    054        int cmp = -Double.compare(nrGroups(s1), nrGroups(s2));
    055        if (cmp != 0)
    056            return cmp;
    057        return super.compare(s1, s2);
    058    }
    059
    060    /**
    061     * Average number of request groups that the student is involved in
    062     * @return number of groups / number of requests
    063     */
    064    public double nrGroups(Student s) {
    065        double nrGroups = 0.0;
    066        for (Request r: s.getRequests()) {
    067            if (r instanceof CourseRequest)
    068                nrGroups += ((CourseRequest)r).getRequestGroups().size();
    069        }
    070        return nrGroups / s.getRequests().size();
    071    }
    072}