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