001package org.cpsolver.studentsct.online.expectations;
002
003import org.cpsolver.ifs.assignment.Assignment;
004import org.cpsolver.ifs.util.DataProperties;
005import org.cpsolver.studentsct.model.Enrollment;
006import org.cpsolver.studentsct.model.Request;
007import org.cpsolver.studentsct.model.Section;
008import org.cpsolver.studentsct.model.Subpart;
009
010/**
011 * Avoid unbalanced sections when there are no expectations. When there are
012 * expectations, the {@link PercentageOverExpected} is used. If there are no
013 * expectations, sections that would have more students than given by the balance
014 * are marked as over-expected. The target fill ratio is proportional to the section
015 * size, a section is considered unbalanced, when the target fill is exceeded by
016 * more than OverExpected.Disbalance percentage (defaults to 0.1). Unlimited
017 * sections are also balanced, when General.BalanceUnlimited parameter is set
018 * to true (defaults to false).<br><br>
019 * A class of an offering with no expectations is over-expected when the number
020 * of enrolled students (including the student in question) minus the target
021 * fill is over the OverExpected.Disbalance portion of the section limit.
022 * 
023 * @author  Tomáš Müller
024 * @version StudentSct 1.3 (Student Sectioning)<br>
025 *          Copyright (C) 2014 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 <a
041 *          href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
042 * 
043 */
044public class AvoidUnbalancedWhenNoExpectations extends PercentageOverExpected {
045    private Double iDisbalance = 0.1;
046    private boolean iBalanceUnlimited = false;
047
048    public AvoidUnbalancedWhenNoExpectations(DataProperties config) {
049        super(config);
050        iDisbalance = config.getPropertyDouble("OverExpected.Disbalance", iDisbalance);
051        iBalanceUnlimited = config.getPropertyBoolean("General.BalanceUnlimited", iBalanceUnlimited);
052    }
053
054    public AvoidUnbalancedWhenNoExpectations(Double percentage, Double disbalance) {
055        super(percentage);
056        iDisbalance = disbalance;
057    }
058
059    public AvoidUnbalancedWhenNoExpectations(Double percentage) {
060        this(percentage, null);
061    }
062
063    public AvoidUnbalancedWhenNoExpectations() {
064        this(null, null);
065    }
066
067    /**
068     * Return allowed disbalance, defaults to 0.1 (parameter OverExpected.Disbalance)
069     * @return allowed disbalance
070     */
071    public Double getDisbalance() {
072        return iDisbalance;
073    }
074
075    /**
076     * Is balancing of unlimited sections enabled (parameter General.BalanceUnlimited)
077     * @return true if balancing of unlimited sections is enabled
078     */
079    public boolean isBalanceUnlimited() {
080        return iBalanceUnlimited;
081    }
082
083    @Override
084    public double getOverExpected(Assignment<Request, Enrollment> assignment, Section section, Request request) {
085        Subpart subpart = section.getSubpart();
086
087        if (hasExpectations(subpart) && section.getLimit() > 0)
088            return super.getOverExpected(assignment, section, request);
089
090        if (getDisbalance() == null || getDisbalance() < 0.0)
091            return 0.0;
092
093        double enrlConfig = request.getWeight() + getEnrollment(assignment, subpart.getConfig(), request);
094        int subparts = section.getSubpart().getConfig().getSubparts().size();
095        int limit = getLimit(section);
096        double enrl = request.getWeight() + getEnrollment(assignment, section, request);
097
098        if (limit > 0) {
099            // sections have limits -> desired size is section limit x (total
100            // enrollment / total limit)
101            double desired = (enrlConfig / getLimit(subpart)) * limit;
102            if (enrl - desired >= Math.max(1.0, getDisbalance() * limit))
103                return 1.0 / subparts;
104        } else if (isBalanceUnlimited()) {
105            // unlimited sections -> desired size is total enrollment / number
106            // of sections
107            double desired = enrlConfig / subpart.getSections().size();
108            if (enrl - desired >= Math.max(1.0, getDisbalance() * desired))
109                return 1.0 / subparts;
110        }
111
112        return 0.0;
113    }
114
115    @Override
116    public String toString() {
117        return "bal(" + getPercentage() + "," + getDisbalance() + ")";
118    }
119
120}