001package org.cpsolver.studentsct.heuristics.selection; 002 003import org.apache.log4j.Logger; 004import org.cpsolver.ifs.assignment.Assignment; 005import org.cpsolver.ifs.model.Neighbour; 006import org.cpsolver.ifs.solution.Solution; 007import org.cpsolver.ifs.solver.Solver; 008import org.cpsolver.ifs.util.DataProperties; 009import org.cpsolver.ifs.util.Progress; 010import org.cpsolver.studentsct.heuristics.studentord.StudentOrder; 011import org.cpsolver.studentsct.heuristics.studentord.StudentRandomOrder; 012import org.cpsolver.studentsct.model.Enrollment; 013import org.cpsolver.studentsct.model.Request; 014import org.cpsolver.studentsct.model.Student; 015 016 017/** 018 * Resection studends with empty schedule. An extension of 019 * {@link BranchBoundSelection}, where only students that have no enrollments ( 020 * {@link Student#nrAssignedRequests(Assignment)} is zero) are resectioned. 021 * 022 * <br> 023 * <br> 024 * 025 * @version StudentSct 1.3 (Student Sectioning)<br> 026 * Copyright (C) 2007 - 2014 Tomáš Müller<br> 027 * <a href="mailto:muller@unitime.org">muller@unitime.org</a><br> 028 * <a href="http://muller.unitime.org">http://muller.unitime.org</a><br> 029 * <br> 030 * This library is free software; you can redistribute it and/or modify 031 * it under the terms of the GNU Lesser General Public License as 032 * published by the Free Software Foundation; either version 3 of the 033 * License, or (at your option) any later version. <br> 034 * <br> 035 * This library is distributed in the hope that it will be useful, but 036 * WITHOUT ANY WARRANTY; without even the implied warranty of 037 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 038 * Lesser General Public License for more details. <br> 039 * <br> 040 * You should have received a copy of the GNU Lesser General Public 041 * License along with this library; if not see 042 * <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>. 043 */ 044 045public class ResectionUnassignedStudentsSelection extends BranchBoundSelection { 046 private static Logger sLog = Logger.getLogger(ResectionUnassignedStudentsSelection.class); 047 048 public ResectionUnassignedStudentsSelection(DataProperties properties) { 049 super(properties); 050 iOrder = new StudentRandomOrder(properties); 051 if (properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder") != null) { 052 try { 053 iOrder = (StudentOrder) Class.forName( 054 properties.getProperty("Neighbour.ResectionUnassignedStudentsOrder")).getConstructor( 055 new Class[] { DataProperties.class }).newInstance(new Object[] { properties }); 056 } catch (Exception e) { 057 sLog.error("Unable to set student order, reason:" + e.getMessage(), e); 058 } 059 } 060 } 061 062 @Override 063 public void init(Solver<Request, Enrollment> solver) { 064 init(solver, "Resection unassigned students..."); 065 } 066 067 /** 068 * Select neighbour. All students with an empty schedule are taken, one by 069 * one in a random order. For each student a branch & bound search is 070 * employed. 071 */ 072 @Override 073 public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) { 074 Student student = null; 075 while ((student = nextStudent()) != null) { 076 Progress.getInstance(solution.getModel()).incProgress(); 077 if (student.nrAssignedRequests(solution.getAssignment()) == 0 && !student.getRequests().isEmpty()) { 078 Neighbour<Request, Enrollment> neighbour = getSelection(solution.getAssignment(), student).select(); 079 if (neighbour != null) 080 return neighbour; 081 } 082 } 083 return null; 084 } 085 086}