001package net.sf.cpsolver.studentsct.heuristics.selection; 002 003import org.apache.log4j.Logger; 004 005import net.sf.cpsolver.ifs.model.Neighbour; 006import net.sf.cpsolver.ifs.solution.Solution; 007import net.sf.cpsolver.ifs.solver.Solver; 008import net.sf.cpsolver.ifs.util.DataProperties; 009import net.sf.cpsolver.ifs.util.Progress; 010import net.sf.cpsolver.studentsct.heuristics.studentord.StudentOrder; 011import net.sf.cpsolver.studentsct.heuristics.studentord.StudentRandomOrder; 012import net.sf.cpsolver.studentsct.model.Enrollment; 013import net.sf.cpsolver.studentsct.model.Request; 014import net.sf.cpsolver.studentsct.model.Student; 015 016/** 017 * Resection studends with empty schedule. An extension of 018 * {@link BranchBoundSelection}, where only students that have no enrollments ( 019 * {@link Student#nrAssignedRequests()} is zero) are resectioned. 020 * 021 * <br> 022 * <br> 023 * 024 * @version StudentSct 1.2 (Student Sectioning)<br> 025 * Copyright (C) 2007 - 2010 Tomáš Müller<br> 026 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 027 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 028 * <br> 029 * This library is free software; you can redistribute it and/or modify 030 * it under the terms of the GNU Lesser General Public License as 031 * published by the Free Software Foundation; either version 3 of the 032 * License, or (at your option) any later version. <br> 033 * <br> 034 * This library is distributed in the hope that it will be useful, but 035 * WITHOUT ANY WARRANTY; without even the implied warranty of 036 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 037 * Lesser General Public License for more details. <br> 038 * <br> 039 * You should have received a copy of the GNU Lesser General Public 040 * License along with this library; if not see 041 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 042 */ 043 044public class ResectionUnassignedStudentsSelection extends BranchBoundSelection { 045 private static Logger sLog = Logger.getLogger(ResectionUnassignedStudentsSelection.class); 046 047 public ResectionUnassignedStudentsSelection(DataProperties properties) { 048 super(properties); 049 iOrder = new StudentRandomOrder(properties); 050 if (properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder") != null) { 051 try { 052 iOrder = (StudentOrder) Class.forName( 053 properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder")).getConstructor( 054 new Class[] { DataProperties.class }).newInstance(new Object[] { properties }); 055 } catch (Exception e) { 056 sLog.error("Unable to set student order, reason:" + e.getMessage(), e); 057 } 058 } 059 } 060 061 @Override 062 public void init(Solver<Request, Enrollment> solver) { 063 init(solver, "Resection unassigned students..."); 064 } 065 066 /** 067 * Select neighbour. All students with an empty schedule are taken, one by 068 * one in a random order. For each student a branch & bound search is 069 * employed. 070 */ 071 @Override 072 public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) { 073 while (iStudentsEnumeration.hasNext()) { 074 Student student = iStudentsEnumeration.next(); 075 Progress.getInstance(solution.getModel()).incProgress(); 076 if (student.nrAssignedRequests() == 0 && !student.getRequests().isEmpty()) { 077 Neighbour<Request, Enrollment> neighbour = getSelection(student).select(); 078 if (neighbour != null) 079 return neighbour; 080 } 081 } 082 return null; 083 } 084 085}