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}