001package net.sf.cpsolver.exam.heuristics; 002 003import java.text.DecimalFormat; 004import java.util.ArrayList; 005import java.util.Collection; 006import java.util.List; 007import java.util.Map; 008 009import net.sf.cpsolver.exam.model.Exam; 010import net.sf.cpsolver.exam.model.ExamPlacement; 011import net.sf.cpsolver.exam.neighbours.ExamRandomMove; 012import net.sf.cpsolver.exam.neighbours.ExamRoomMove; 013import net.sf.cpsolver.exam.neighbours.ExamTimeMove; 014import net.sf.cpsolver.ifs.heuristics.NeighbourSelection; 015import net.sf.cpsolver.ifs.model.LazyNeighbour; 016import net.sf.cpsolver.ifs.model.Neighbour; 017import net.sf.cpsolver.ifs.model.LazyNeighbour.LazyNeighbourAcceptanceCriterion; 018import net.sf.cpsolver.ifs.solution.Solution; 019import net.sf.cpsolver.ifs.solution.SolutionListener; 020import net.sf.cpsolver.ifs.solver.Solver; 021import net.sf.cpsolver.ifs.util.DataProperties; 022import net.sf.cpsolver.ifs.util.JProf; 023import net.sf.cpsolver.ifs.util.Progress; 024import net.sf.cpsolver.ifs.util.ToolBox; 025 026import org.apache.log4j.Logger; 027 028/** 029 * Greate deluge. In each iteration, one of the following three neighbourhoods 030 * is selected first 031 * <ul> 032 * <li>random move ({@link ExamRandomMove}) 033 * <li>period swap ({@link ExamTimeMove}) 034 * <li>room swap ({@link ExamRoomMove}) 035 * </ul> 036 * , then a neighbour is generated and it is accepted if the value of the new 037 * solution is below certain bound. This bound is initialized to the 038 * GreatDeluge.UpperBoundRate × value of the best solution ever found. 039 * After each iteration, the bound is decreased by GreatDeluge.CoolRate (new 040 * bound equals to old bound × GreatDeluge.CoolRate). If the bound gets 041 * bellow GreatDeluge.LowerBoundRate × value of the best solution ever 042 * found, it is changed back to GreatDeluge.UpperBoundRate × value of the 043 * best solution ever found. 044 * 045 * If there was no improvement found between the bounds, the new bounds are 046 * changed to GreatDeluge.UpperBoundRate^2 and GreatDeluge.LowerBoundRate^2, 047 * GreatDeluge.UpperBoundRate^3 and GreatDeluge.LowerBoundRate^3, etc. till 048 * there is an improvement found. <br> 049 * <br> 050 * 051 * @version ExamTT 1.2 (Examination Timetabling)<br> 052 * Copyright (C) 2008 - 2010 Tomáš Müller<br> 053 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 054 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 055 * <br> 056 * This library is free software; you can redistribute it and/or modify 057 * it under the terms of the GNU Lesser General Public License as 058 * published by the Free Software Foundation; either version 3 of the 059 * License, or (at your option) any later version. <br> 060 * <br> 061 * This library is distributed in the hope that it will be useful, but 062 * WITHOUT ANY WARRANTY; without even the implied warranty of 063 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 064 * Lesser General Public License for more details. <br> 065 * <br> 066 * You should have received a copy of the GNU Lesser General Public 067 * License along with this library; if not see 068 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 069 */ 070public class ExamGreatDeluge implements NeighbourSelection<Exam, ExamPlacement>, SolutionListener<Exam, ExamPlacement>, LazyNeighbourAcceptanceCriterion<Exam, ExamPlacement> { 071 private static Logger sLog = Logger.getLogger(ExamGreatDeluge.class); 072 private static DecimalFormat sDF2 = new DecimalFormat("0.00"); 073 private static DecimalFormat sDF5 = new DecimalFormat("0.00000"); 074 private double iBound = 0.0; 075 private double iCoolRate = 0.99999995; 076 private long iIter; 077 private double iUpperBound; 078 private double iUpperBoundRate = 1.05; 079 private double iLowerBoundRate = 0.95; 080 private int iMoves = 0; 081 private int iAcceptedMoves = 0; 082 private int iNrIdle = 0; 083 private long iT0 = -1; 084 private long iLastImprovingIter = 0; 085 private double iBestValue = 0; 086 private Progress iProgress = null; 087 088 private List<NeighbourSelection<Exam, ExamPlacement>> iNeighbours = null; 089 090 /** 091 * Constructor. Following problem properties are considered: 092 * <ul> 093 * <li>GreatDeluge.CoolRate ... bound cooling rate (default 0.99999995) 094 * <li>GreatDeluge.UpperBoundRate ... bound upper bound relative to best 095 * solution ever found (default 1.05) 096 * <li>GreatDeluge.LowerBoundRate ... bound lower bound relative to best 097 * solution ever found (default 0.95) 098 * </ul> 099 * 100 * @param properties 101 * problem properties 102 */ 103 @SuppressWarnings("unchecked") 104 public ExamGreatDeluge(DataProperties properties) { 105 iCoolRate = properties.getPropertyDouble("GreatDeluge.CoolRate", iCoolRate); 106 iUpperBoundRate = properties.getPropertyDouble("GreatDeluge.UpperBoundRate", iUpperBoundRate); 107 iLowerBoundRate = properties.getPropertyDouble("GreatDeluge.LowerBoundRate", iLowerBoundRate); 108 String neighbours = properties.getProperty("GreatDeluge.Neighbours", 109 ExamRandomMove.class.getName() + ";" + 110 ExamRoomMove.class.getName() + ";" + 111 ExamTimeMove.class.getName()); 112 neighbours += ";" + properties.getProperty("GreatDeluge.AdditionalNeighbours", ""); 113 iNeighbours = new ArrayList<NeighbourSelection<Exam,ExamPlacement>>(); 114 for (String neighbour: neighbours.split("\\;")) { 115 if (neighbour == null || neighbour.isEmpty()) continue; 116 try { 117 Class<NeighbourSelection<Exam, ExamPlacement>> clazz = (Class<NeighbourSelection<Exam, ExamPlacement>>)Class.forName(neighbour); 118 iNeighbours.add(clazz.getConstructor(DataProperties.class).newInstance(properties)); 119 } catch (Exception e) { 120 sLog.error("Unable to use " + neighbour + ": " + e.getMessage()); 121 } 122 } 123 } 124 125 /** Initialization */ 126 @Override 127 public void init(Solver<Exam, ExamPlacement> solver) { 128 iIter = -1; 129 solver.currentSolution().addSolutionListener(this); 130 for (NeighbourSelection<Exam, ExamPlacement> neighbour: iNeighbours) 131 neighbour.init(solver); 132 solver.setUpdateProgress(false); 133 iProgress = Progress.getInstance(solver.currentSolution().getModel()); 134 } 135 136 /** Print some information */ 137 protected void info(Solution<Exam, ExamPlacement> solution) { 138 sLog.info("Iter=" + iIter / 1000 + "k, NonImpIter=" + sDF2.format((iIter - iLastImprovingIter) / 1000.0) 139 + "k, Speed=" + sDF2.format(1000.0 * iIter / (JProf.currentTimeMillis() - iT0)) + " it/s"); 140 sLog.info("Bound is " + sDF2.format(iBound) + ", " + "best value is " + sDF2.format(solution.getBestValue()) 141 + " (" + sDF2.format(100.0 * iBound / solution.getBestValue()) + "%), " + "current value is " 142 + sDF2.format(solution.getModel().getTotalValue()) + " (" 143 + sDF2.format(100.0 * iBound / solution.getModel().getTotalValue()) + "%), " + "#idle=" + iNrIdle 144 + ", " + "Pacc=" + sDF5.format(100.0 * iAcceptedMoves / iMoves) + "%"); 145 iAcceptedMoves = iMoves = 0; 146 } 147 148 /** 149 * Generate neighbour -- select neighbourhood randomly, select neighbour 150 */ 151 public Neighbour<Exam, ExamPlacement> genMove(Solution<Exam, ExamPlacement> solution) { 152 while (true) { 153 incIter(solution); 154 NeighbourSelection<Exam, ExamPlacement> ns = iNeighbours.get(ToolBox.random(iNeighbours.size())); 155 Neighbour<Exam, ExamPlacement> n = ns.selectNeighbour(solution); 156 if (n != null) 157 return n; 158 } 159 } 160 161 /** Accept neighbour */ 162 protected boolean accept(Solution<Exam, ExamPlacement> solution, Neighbour<Exam, ExamPlacement> neighbour) { 163 if (neighbour instanceof LazyNeighbour) { 164 ((LazyNeighbour<Exam, ExamPlacement>)neighbour).setAcceptanceCriterion(this); 165 return true; 166 } 167 return (neighbour.value() <= 0 || solution.getModel().getTotalValue() + neighbour.value() <= iBound); 168 } 169 170 /** Accept lazy neighbour */ 171 @Override 172 public boolean accept(LazyNeighbour<Exam, ExamPlacement> neighbour, double value) { 173 return (value <= 0.0 || neighbour.getModel().getTotalValue() <= iBound); 174 } 175 176 /** Increment iteration count, update bound */ 177 protected void incIter(Solution<Exam, ExamPlacement> solution) { 178 if (iIter < 0) { 179 iIter = 0; 180 iLastImprovingIter = 0; 181 iT0 = JProf.currentTimeMillis(); 182 iBound = (solution.getBestValue() > 0.0 ? iUpperBoundRate * solution.getBestValue() : solution 183 .getBestValue() 184 / iUpperBoundRate); 185 iUpperBound = iBound; 186 iNrIdle = 0; 187 iProgress.setPhase("Great deluge [" + (1 + iNrIdle) + "]..."); 188 } else { 189 iIter++; 190 if (solution.getBestValue() >= 0.0) 191 iBound *= iCoolRate; 192 else 193 iBound /= iCoolRate; 194 } 195 if (iIter % 100000 == 0) { 196 info(solution); 197 } 198 double lowerBound = (solution.getBestValue() >= 0.0 ? Math.pow(iLowerBoundRate, 1 + iNrIdle) 199 * solution.getBestValue() : solution.getBestValue() / Math.pow(iLowerBoundRate, 1 + iNrIdle)); 200 if (iBound < lowerBound) { 201 iNrIdle++; 202 sLog.info(" -<[" + iNrIdle + "]>- "); 203 iBound = Math.max(solution.getBestValue() + 2.0, (solution.getBestValue() >= 0.0 ? Math.pow( 204 iUpperBoundRate, iNrIdle) 205 * solution.getBestValue() : solution.getBestValue() / Math.pow(iUpperBoundRate, iNrIdle))); 206 iUpperBound = iBound; 207 iProgress.setPhase("Great deluge [" + (1 + iNrIdle) + "]..."); 208 } 209 iProgress.setProgress(100 - Math.round(100.0 * (iBound - lowerBound) / (iUpperBound - lowerBound))); 210 } 211 212 /** 213 * A neighbour is generated randomly untill an acceptable one is found. 214 */ 215 @Override 216 public Neighbour<Exam, ExamPlacement> selectNeighbour(Solution<Exam, ExamPlacement> solution) { 217 Neighbour<Exam, ExamPlacement> neighbour = null; 218 while ((neighbour = genMove(solution)) != null) { 219 iMoves++; 220 if (accept(solution, neighbour)) { 221 iAcceptedMoves++; 222 break; 223 } 224 } 225 return (neighbour == null ? null : neighbour); 226 } 227 228 /** Update last improving iteration count */ 229 @Override 230 public void bestSaved(Solution<Exam, ExamPlacement> solution) { 231 if (Math.abs(iBestValue - solution.getBestValue()) >= 1.0) { 232 iLastImprovingIter = iIter; 233 iNrIdle = 0; 234 iBestValue = solution.getBestValue(); 235 } 236 } 237 238 @Override 239 public void solutionUpdated(Solution<Exam, ExamPlacement> solution) { 240 } 241 242 @Override 243 public void getInfo(Solution<Exam, ExamPlacement> solution, Map<String, String> info) { 244 } 245 246 @Override 247 public void getInfo(Solution<Exam, ExamPlacement> solution, Map<String, String> info, Collection<Exam> variables) { 248 } 249 250 @Override 251 public void bestCleared(Solution<Exam, ExamPlacement> solution) { 252 } 253 254 @Override 255 public void bestRestored(Solution<Exam, ExamPlacement> solution) { 256 } 257}