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 * @version StudentSct 1.3 (Student Sectioning)<br>
024 *          Copyright (C) 2014 Tomáš Müller<br>
025 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
026 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
027 * <br>
028 *          This library is free software; you can redistribute it and/or modify
029 *          it under the terms of the GNU Lesser General Public License as
030 *          published by the Free Software Foundation; either version 3 of the
031 *          License, or (at your option) any later version. <br>
032 * <br>
033 *          This library is distributed in the hope that it will be useful, but
034 *          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. <br>
037 * <br>
038 *          You should have received a copy of the GNU Lesser General Public
039 *          License along with this library; if not see <a
040 *          href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
041 * 
042 */
043public class AvoidUnbalancedWhenNoExpectations extends PercentageOverExpected {
044    private Double iDisbalance = 0.1;
045    private boolean iBalanceUnlimited = false;
046
047    public AvoidUnbalancedWhenNoExpectations(DataProperties config) {
048        super(config);
049        iDisbalance = config.getPropertyDouble("OverExpected.Disbalance", iDisbalance);
050        iBalanceUnlimited = config.getPropertyBoolean("General.BalanceUnlimited", iBalanceUnlimited);
051    }
052
053    public AvoidUnbalancedWhenNoExpectations(Double percentage, Double disbalance) {
054        super(percentage);
055        iDisbalance = disbalance;
056    }
057
058    public AvoidUnbalancedWhenNoExpectations(Double percentage) {
059        this(percentage, null);
060    }
061
062    public AvoidUnbalancedWhenNoExpectations() {
063        this(null, null);
064    }
065
066    /**
067     * Return allowed disbalance, defaults to 0.1 (parameter OverExpected.Disbalance)
068     * @return allowed disbalance
069     */
070    public Double getDisbalance() {
071        return iDisbalance;
072    }
073
074    /**
075     * Is balancing of unlimited sections enabled (parameter General.BalanceUnlimited)
076     * @return true if balancing of unlimited sections is enabled
077     */
078    public boolean isBalanceUnlimited() {
079        return iBalanceUnlimited;
080    }
081
082    @Override
083    public double getOverExpected(Assignment<Request, Enrollment> assignment, Section section, Request request) {
084        Subpart subpart = section.getSubpart();
085
086        if (hasExpectations(subpart) && section.getLimit() > 0)
087            return super.getOverExpected(assignment, section, request);
088
089        if (getDisbalance() == null || getDisbalance() < 0.0)
090            return 0.0;
091
092        double enrlConfig = request.getWeight() + getEnrollment(assignment, subpart.getConfig(), request);
093        int subparts = section.getSubpart().getConfig().getSubparts().size();
094        int limit = getLimit(section);
095        double enrl = request.getWeight() + getEnrollment(assignment, section, request);
096
097        if (limit > 0) {
098            // sections have limits -> desired size is section limit x (total
099            // enrollment / total limit)
100            double desired = (enrlConfig / getLimit(subpart)) * limit;
101            if (enrl - desired >= Math.max(1.0, getDisbalance() * limit))
102                return 1.0 / subparts;
103        } else if (isBalanceUnlimited()) {
104            // unlimited sections -> desired size is total enrollment / number
105            // of sections
106            double desired = enrlConfig / subpart.getSections().size();
107            if (enrl - desired >= Math.max(1.0, getDisbalance() * desired))
108                return 1.0 / subparts;
109        }
110
111        return 0.0;
112    }
113
114    @Override
115    public String toString() {
116        return "bal(" + getPercentage() + "," + getDisbalance() + ")";
117    }
118
119}