001 package net.sf.cpsolver.studentsct.heuristics.selection; 002 003 import org.apache.log4j.Logger; 004 005 import net.sf.cpsolver.ifs.model.Neighbour; 006 import net.sf.cpsolver.ifs.solution.Solution; 007 import net.sf.cpsolver.ifs.solver.Solver; 008 import net.sf.cpsolver.ifs.util.DataProperties; 009 import net.sf.cpsolver.ifs.util.Progress; 010 import net.sf.cpsolver.studentsct.heuristics.studentord.StudentOrder; 011 import net.sf.cpsolver.studentsct.heuristics.studentord.StudentRandomOrder; 012 import net.sf.cpsolver.studentsct.model.Student; 013 014 /** 015 * Resection studends with empty schedule. 016 * An extension of {@link BranchBoundSelection}, where only students that have 017 * no enrollments ({@link Student#nrAssignedRequests()} is zero) are 018 * resectioned. 019 * 020 * <br><br> 021 * 022 * @version 023 * StudentSct 1.1 (Student Sectioning)<br> 024 * Copyright (C) 2007 Tomáš Müller<br> 025 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 026 * Lazenska 391, 76314 Zlin, Czech Republic<br> 027 * <br> 028 * This library is free software; you can redistribute it and/or 029 * modify it under the terms of the GNU Lesser General Public 030 * License as published by the Free Software Foundation; either 031 * version 2.1 of the License, or (at your option) any later version. 032 * <br><br> 033 * This library is distributed in the hope that it will be useful, 034 * but WITHOUT ANY WARRANTY; without even the implied warranty of 035 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 036 * Lesser General Public License for more details. 037 * <br><br> 038 * You should have received a copy of the GNU Lesser General Public 039 * License along with this library; if not, write to the Free Software 040 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 041 */ 042 043 public class ResectionUnassignedStudentsSelection extends BranchBoundSelection { 044 private static Logger sLog = Logger.getLogger(ResectionUnassignedStudentsSelection.class); 045 046 public ResectionUnassignedStudentsSelection(DataProperties properties) { 047 super(properties); 048 iOrder = new StudentRandomOrder(properties); 049 if (properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder")!=null) { 050 try { 051 iOrder = (StudentOrder)Class.forName(properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder")). 052 getConstructor(new Class[] {DataProperties.class}). 053 newInstance(new Object[] {properties}); 054 } catch (Exception e) { 055 sLog.error("Unable to set student order, reason:"+e.getMessage(),e); 056 } 057 } 058 } 059 060 public void init(Solver solver) { 061 init(solver, "Resection unassigned students..."); 062 } 063 064 /** 065 * Select neighbour. All students with an empty schedule are taken, 066 * one by one in a random order. For each student a branch & bound search is employed. 067 */ 068 public Neighbour selectNeighbour(Solution solution) { 069 while (iStudentsEnumeration.hasMoreElements()) { 070 Student student = (Student)iStudentsEnumeration.nextElement(); 071 Progress.getInstance(solution.getModel()).incProgress(); 072 if (student.nrAssignedRequests()==0 && !student.getRequests().isEmpty()) { 073 Neighbour neighbour = getSelection(student).select(); 074 if (neighbour!=null) return neighbour; 075 } 076 } 077 return null; 078 } 079 080 }