001package net.sf.cpsolver.exam.criteria;
002
003import java.util.Map;
004import java.util.Set;
005
006import net.sf.cpsolver.exam.model.Exam;
007import net.sf.cpsolver.exam.model.ExamPeriod;
008import net.sf.cpsolver.exam.model.ExamPlacement;
009import net.sf.cpsolver.exam.model.ExamStudent;
010import net.sf.cpsolver.ifs.solver.Solver;
011import net.sf.cpsolver.ifs.util.DataProperties;
012
013/**
014 * Number of back-to-back student conflicts. I.e., number of cases when
015 * an exam is attended by a student that attends some other exam at
016 * the previous {@link ExamPeriod#prev()} or following
017 * {@link ExamPeriod#next()} period. If
018 * {@link StudentBackToBackConflicts#isDayBreakBackToBack()} is false, back-to-back conflicts
019 * are only considered between consecutive periods that are of the same day.
020 * <br><br>
021 * Back-to-back student conflict weight can be set by problem property
022 * Exams.BackToBackConflictWeight, or in the input xml file,
023 * property backToBackConflictWeight.
024 * 
025 * 
026 * <br>
027 * 
028 * @version ExamTT 1.2 (Examination Timetabling)<br>
029 *          Copyright (C) 2008 - 2012 Tomáš Müller<br>
030 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
031 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
032 * <br>
033 *          This library is free software; you can redistribute it and/or modify
034 *          it under the terms of the GNU Lesser General Public License as
035 *          published by the Free Software Foundation; either version 3 of the
036 *          License, or (at your option) any later version. <br>
037 * <br>
038 *          This library is distributed in the hope that it will be useful, but
039 *          WITHOUT ANY WARRANTY; without even the implied warranty of
040 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
041 *          Lesser General Public License for more details. <br>
042 * <br>
043 *          You should have received a copy of the GNU Lesser General Public
044 *          License along with this library; if not see
045 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
046 */
047public class StudentBackToBackConflicts extends ExamCriterion {
048    private boolean iDayBreakBackToBack = false;
049    
050    @Override
051    public boolean init(Solver<Exam, ExamPlacement> solver) {
052        boolean ret = super.init(solver);
053        iDayBreakBackToBack = solver.getProperties().getPropertyBoolean("Exams.IsDayBreakBackToBack", iDayBreakBackToBack);
054        return ret;
055    }
056        
057    @Override
058    public String getWeightName() {
059        return "Exams.BackToBackConflictWeight";
060    }
061    
062    @Override
063    public String getXmlWeightName() {
064        return "backToBackConflictWeight";
065    }
066    
067    @Override
068    public double getWeightDefault(DataProperties config) {
069        return 10.0;
070    }
071
072    /**
073     * True when back-to-back student conflict is to be encountered when a
074     * student is enrolled into an exam that is on the last period of one day
075     * and another exam that is on the first period of the consecutive day. It
076     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
077     * input xml file, property isDayBreakBackToBack)
078     */
079    public boolean isDayBreakBackToBack() {
080        return iDayBreakBackToBack;
081    }
082    
083    /**
084     * True when back-to-back student conflict is to be encountered when a
085     * student is enrolled into an exam that is on the last period of one day
086     * and another exam that is on the first period of the consecutive day. It
087     * can be set by problem property Exams.IsDayBreakBackToBack, or in the
088     * input xml file, property isDayBreakBackToBack)
089     * 
090     */
091    public void setDayBreakBackToBack(boolean dayBreakBackToBack) {
092        iDayBreakBackToBack = dayBreakBackToBack;
093    }
094    
095    @Override
096    public void getXmlParameters(Map<String, String> params) {
097        params.put(getXmlWeightName(), String.valueOf(getWeight()));
098        params.put("isDayBreakBackToBack", isDayBreakBackToBack() ? "true" : "false");
099    }
100    
101    @Override
102    public void setXmlParameters(Map<String, String> params) {
103        try {
104            setWeight(Double.valueOf(params.get(getXmlWeightName())));
105        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
106        try {
107            setDayBreakBackToBack("true".equals(params.get("isDayBreakBackToBack")));
108        } catch (NumberFormatException e) {} catch (NullPointerException e) {}
109    }
110    
111    @Override
112    public double getValue(ExamPlacement value, Set<ExamPlacement> conflicts) {
113        Exam exam = value.variable();
114        int penalty = 0;
115        for (ExamStudent s : exam.getStudents()) {
116            if (value.getPeriod().prev() != null) {
117                if (isDayBreakBackToBack() || value.getPeriod().prev().getDay() == value.getPeriod().getDay()) {
118                    Set<Exam> exams = s.getExams(value.getPeriod().prev());
119                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
120                    penalty += nrExams;
121                }
122            }
123            if (value.getPeriod().next() != null) {
124                if (isDayBreakBackToBack() || value.getPeriod().next().getDay() == value.getPeriod().getDay()) {
125                    Set<Exam> exams = s.getExams(value.getPeriod().next());
126                    int nrExams = exams.size() + (exams.contains(exam) ? -1 : 0);
127                    penalty += nrExams;
128                }
129            }
130        }
131        return penalty;
132    }
133    
134    @Override
135    public String getName() {
136        return "Back-To-Back Conflicts";
137    }
138    
139    @Override
140    public void getInfo(Map<String, String> info) {
141        if (getValue() != 0.0)
142            info.put(getName(), sDoubleFormat.format(getValue()));
143    }
144    
145    @Override
146    public String toString() {
147        return "BTB:" + sDoubleFormat.format(getValue());
148    }
149}