001package org.cpsolver.exam.criteria;
002
003import java.util.Collection;
004import java.util.Map;
005import java.util.Set;
006
007import org.cpsolver.exam.model.Exam;
008import org.cpsolver.exam.model.ExamModel;
009import org.cpsolver.exam.model.ExamPeriod;
010import org.cpsolver.exam.model.ExamPlacement;
011import org.cpsolver.exam.model.ExamStudent;
012import org.cpsolver.ifs.assignment.Assignment;
013import org.cpsolver.ifs.util.DataProperties;
014
015
016/**
017 * Number of direct student conflicts. I.e., number of cases when an
018 * exam is attended by a student that attends some other exam at the
019 * same period.
020 * <br><br>
021 * Direct student conflict weight can be set by problem property
022 * Exams.DirectConflictWeight, or in the input xml file, property
023 * directConflictWeight.
024 * 
025 * <br>
026 * 
027 * @version ExamTT 1.3 (Examination Timetabling)<br>
028 *          Copyright (C) 2008 - 2014 Tomáš Müller<br>
029 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
030 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
031 * <br>
032 *          This library is free software; you can redistribute it and/or modify
033 *          it under the terms of the GNU Lesser General Public License as
034 *          published by the Free Software Foundation; either version 3 of the
035 *          License, or (at your option) any later version. <br>
036 * <br>
037 *          This library is distributed in the hope that it will be useful, but
038 *          WITHOUT ANY WARRANTY; without even the implied warranty of
039 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
040 *          Lesser General Public License for more details. <br>
041 * <br>
042 *          You should have received a copy of the GNU Lesser General Public
043 *          License along with this library; if not see
044 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
045 */
046public class StudentDirectConflicts extends ExamCriterion {
047    
048    @Override
049    public String getWeightName() {
050        return "Exams.DirectConflictWeight";
051    }
052    
053    @Override
054    public String getXmlWeightName() {
055        return "directConflictWeight";
056    }
057
058    @Override
059    public double getWeightDefault(DataProperties config) {
060        return 1000.0;
061    }
062    
063    @Override
064    public double getValue(Assignment<Exam, ExamPlacement> assignment, ExamPlacement value, Set<ExamPlacement> conflicts) {
065        Exam exam = value.variable();
066        int penalty = 0;
067        ExamPeriod period = value.getPeriod();
068        ExamModel m = (ExamModel)getModel();
069        Map<ExamStudent, Set<Exam>> students = m.getStudentsOfPeriod(assignment, period);
070        for (ExamStudent s : exam.getStudents()) {
071            Set<Exam> exams = students.get(s);
072            if (exams == null) continue;
073            int nrExams = exams.size() + (exams.contains(exam) ? 0 : 1);
074            if (nrExams > 1)
075                penalty++;
076        }
077        if (m.isCheckForPeriodOverlaps()) {
078            for (ExamPeriod p: m.getPeriods()) {
079                if (period.hasIntersection(p)) {
080                    Map<ExamStudent, Set<Exam>> others = m.getStudentsOfPeriod(assignment, p);
081                    s: for (ExamStudent s : exam.getStudents()) {
082                        Set<Exam> exams = students.get(s);
083                        if (exams == null || exams.size() + (exams.contains(exam) ? 0 : 1) <= 1) {
084                            Set<Exam> other = others.get(s);
085                            if (other != null && !other.isEmpty())
086                                for (Exam x: other) {
087                                    if (period.hasIntersection(exam, x, p)) {
088                                        penalty ++; continue s;
089                                    }
090                                }
091                        }
092                    }
093                }
094            }
095        }
096        /*
097        for (ExamStudent s : exam.getStudents()) {
098            Set<Exam> exams = s.getExams(assignment, period);
099            if (exams.isEmpty()) continue;
100            int nrExams = exams.size() + (exams.contains(exam) ? 0 : 1);
101            if (nrExams > 1)
102                penalty++;
103        }
104        */
105        return penalty;
106    }
107
108    @Override
109    public String getName() {
110        return "Direct Conflicts";
111    }
112    
113    @Override
114    public void getInfo(Assignment<Exam, ExamPlacement> assignment, Map<String, String> info) {
115        StudentNotAvailableConflicts na = (StudentNotAvailableConflicts)getModel().getCriterion(StudentNotAvailableConflicts.class);
116        if (getValue(assignment) != 0.0 || (na != null && na.getValue(assignment) != 0.0))
117            info.put(getName(), sDoubleFormat.format(getValue(assignment) + (na == null ? 0.0 : na.getValue(assignment))) +
118                    (na == null || na.getValue(assignment) == 0.0 ? "" : " (" + sDoubleFormat.format(na.getValue(assignment)) + " N/A)"));
119    }
120    
121    @Override
122    public double getValue(Assignment<Exam, ExamPlacement> assignment, Collection<Exam> variables) {
123        int ret = 0;
124        ExamModel m = (ExamModel)getModel();
125        for (ExamPeriod p: m.getPeriods()) {
126            Map<ExamStudent, Set<Exam>> students = ((ExamModel)getModel()).getStudentsOfPeriod(assignment, p);
127            for (Set<Exam> exams: students.values()) {
128                int nrExams = exams.size();
129                if (nrExams > 1)
130                    ret += nrExams - 1;
131            }
132        }
133        if (m.isCheckForPeriodOverlaps()) {
134            for (ExamPeriod p: m.getPeriods()) {
135                for (ExamPeriod q: m.getPeriods()) {
136                    if (p.getIndex() < q.getIndex() && p.hasIntersection(q)) {
137                        Map<ExamStudent, Set<Exam>> s1 = m.getStudentsOfPeriod(assignment, p);
138                        Map<ExamStudent, Set<Exam>> s2 = m.getStudentsOfPeriod(assignment, q);
139                        for (Map.Entry<ExamStudent, Set<Exam>> e: s1.entrySet()) {
140                            ExamStudent s = e.getKey();
141                            if (!e.getValue().isEmpty()) {
142                                Set<Exam> x = s2.get(s);
143                                if (x != null && x.isEmpty()) {
144                                    x1: for (Exam x1: e.getValue()) {
145                                        for (Exam x2: x) {
146                                            if (p.hasIntersection(x1, x2, q)) {
147                                                ret += 1; break x1;
148                                            }
149                                        }
150                                    }
151                                }
152                            }
153                        }
154                    }
155                }
156            }
157        }
158        return ret;
159    }
160
161    @Override
162    public String toString(Assignment<Exam, ExamPlacement> assignment) {
163        return "DC:" + sDoubleFormat.format(getValue(assignment));
164    }
165}