    001package org.cpsolver.studentsct.heuristics.studentord;
    002
    003import java.util.ArrayList;
    004import java.util.Collections;
    005import java.util.Comparator;
    006import java.util.HashSet;
    007import java.util.HashMap;
    008import java.util.List;
    009
    010import org.cpsolver.ifs.util.DataProperties;
    011import org.cpsolver.studentsct.model.Config;
    012import org.cpsolver.studentsct.model.Course;
    013import org.cpsolver.studentsct.model.CourseRequest;
    014import org.cpsolver.studentsct.model.Request;
    015import org.cpsolver.studentsct.model.Request.RequestPriority;
    016import org.cpsolver.studentsct.model.Section;
    017import org.cpsolver.studentsct.model.Student;
    018import org.cpsolver.studentsct.model.Subpart;
    019
    020
    021/**
    022 * Return the given set of students in an order of average number of choices of
    023 * each student (students with more choices first).
    024 *
    025 * @author  Tomáš Müller
    026 * @version StudentSct 1.3 (Student Sectioning)<br>
    027 *          Copyright (C) 2007 - 2014 Tomáš Müller<br>
    028 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    029 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    030 * <br>
    031 *          This library is free software; you can redistribute it and/or modify
    032 *          it under the terms of the GNU Lesser General Public License as
    033 *          published by the Free Software Foundation; either version 3 of the
    034 *          License, or (at your option) any later version. <br>
    035 * <br>
    036 *          This library is distributed in the hope that it will be useful, but
    037 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    038 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    039 *          Lesser General Public License for more details. <br>
    040 * <br>
    041 *          You should have received a copy of the GNU Lesser General Public
    042 *          License along with this library; if not see
    043 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    044 */
    045public class StudentChoiceOrder implements StudentOrder, Comparator<Student> {
    046    private boolean iReverse = false;
    047    private boolean iFast = true;
    048    private boolean iCriticalOnly = false;
    049    private RequestPriority iPriority = RequestPriority.Critical;
    050    private HashMap<Config, Integer> iCache = new HashMap<Config, Integer>();
    051
    052    public StudentChoiceOrder(DataProperties config) {
    053        iReverse = config.getPropertyBoolean("StudentChoiceOrder.Reverse", iReverse);
    054        iFast = config.getPropertyBoolean("StudentChoiceOrder.Fast", iFast);
    055        iCriticalOnly = config.getPropertyBoolean("StudentChoiceOrder.CriticalOnly", iCriticalOnly);
    056    }
    057
    058    /** Is order reversed
    059     * @return true if the order is reversed
    060     **/
    061    public boolean isReverse() {
    062        return iReverse;
    063    }
    064
    065    /** Set reverse order
    066     * @param reverse true if students are to be in a reversed order
    067     **/
    068    public void setReverse(boolean reverse) {
    069        iReverse = reverse;
    070    }
    071
    072    public boolean isCriticalOnly() { return iCriticalOnly; }
    073    public void setCriticalOnly(boolean critOnly) { iCriticalOnly = critOnly; }
    074    public void setRequestPriority(RequestPriority priority) { iPriority = priority; }
    075    public RequestPriority getRequestPriority() { return iPriority; }
    076
    077    /** Order the given list of students */
    078    @Override
    079    public List<Student> order(List<Student> students) {
    080        List<Student> ret = new ArrayList<Student>(students);
    081        Collections.sort(ret, this);
    082        return ret;
    083    }
    084
    085    @Override
    086    public int compare(Student s1, Student s2) {
    087        if (s1.getPriority() != s2.getPriority()) return (s1.getPriority().ordinal() < s2.getPriority().ordinal() ? -1 : 1);
    088        try {
    089            int cmp = -Double.compare(avgNrChoices(s1), avgNrChoices(s2));
    090            if (cmp != 0)
    091                return (iReverse ? -1 : 1) * cmp;
    092        } catch (Exception e) {
    093            e.printStackTrace();
    094        }
    095        return (iReverse ? -1 : 1) * Double.compare(s1.getId(), s2.getId());
    096    }
    097
    098    private int nrChoices(Config config, int idx, HashSet<Section> sections) {
    099        if (iFast) {
    100            int nrChoices = 1;
    101            for (Subpart subpart: config.getSubparts()) {
    102                if (subpart.getChildren().isEmpty())
    103                    nrChoices *= subpart.getSections().size();
    104            }
    105            return nrChoices;
    106        }
    107        if (config.getSubparts().size() == idx) {
    108            return 1;
    109        } else {
    110            Subpart subpart = config.getSubparts().get(idx);
    111            int choicesThisSubpart = 0;
    112            for (Section section : subpart.getSections()) {
    113                if (section.getParent() != null && !sections.contains(section.getParent()))
    114                    continue;
    115                if (section.isOverlapping(sections))
    116                    continue;
    117                sections.add(section);
    118                choicesThisSubpart += nrChoices(config, idx + 1, sections);
    119                sections.remove(section);
    120            }
    121            return choicesThisSubpart;
    122        }
    123    }
    124
    125    /** Average number of choices for each student
    126     * @param student given student
    127     * @return average number of choices of the given student
    128     **/
    129    public double avgNrChoices(Student student) {
    130        int nrRequests = 0;
    131        int nrChoices = 0;
    132        for (Request request : student.getRequests()) {
    133            if (request instanceof CourseRequest) {
    134                CourseRequest cr = (CourseRequest) request;
    135                if (iCriticalOnly && (!iPriority.isCritical(cr) || cr.isAlternative())) continue;
    136                for (Course course : cr.getCourses()) {
    137                    for (Config config : course.getOffering().getConfigs()) {
    138                        Integer nrChoicesThisCfg = iCache.get(config);
    139                        if (nrChoicesThisCfg == null) {
    140                            nrChoicesThisCfg = Integer.valueOf(nrChoices(config, 0, new HashSet<Section>()));
    141                            iCache.put(config, nrChoicesThisCfg);
    142                        }
    143                        nrChoices += nrChoicesThisCfg.intValue();
    144                    }
    145                }
    146                nrRequests++;
    147            }
    148        }
    149        return (nrRequests == 0 ? 0.0 : ((double) nrChoices) / nrRequests);
    150    }
    151}