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 FractionallyOverExpected} is used. If there are no
013 * expectations, sections that would have more students than given by the
014 * balance are marked as over-expected. The target fill ratio is proportional to
015 * the section size, a section is considered unbalanced, when the target fill is
016 * exceeded by more than OverExpected.Disbalance percentage (defaults to 0.1).
017 * Unlimited sections are also balanced, when General.BalanceUnlimited parameter
018 * is set to true (defaults to false).<br>
019 * <br>
020 * A class of an offering with no expectations is over-expected when the number
021 * of enrolled students (including the student in question) minus the target
022 * fill is over the OverExpected.Disbalance portion of the section limit.
023 * 
024 * @author  Tomáš Müller
025 * @version StudentSct 1.3 (Student Sectioning)<br>
026 *          Copyright (C) 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 <a
042 *          href='http://www.gnu.org/licenses'>http://www.gnu.org/licenses</a>.
043 * 
044 */
045public class FractionallyUnbalancedWhenNoExpectations extends FractionallyOverExpected {
046    private Double iDisbalance = 0.1;
047    private boolean iBalanceUnlimited = false;
048
049    public FractionallyUnbalancedWhenNoExpectations(DataProperties config) {
050        super(config);
051        iDisbalance = config.getPropertyDouble("OverExpected.Disbalance", iDisbalance);
052        iBalanceUnlimited = config.getPropertyBoolean("General.BalanceUnlimited", iBalanceUnlimited);
053    }
054
055    public FractionallyUnbalancedWhenNoExpectations(Double percentage, Double maximum, Double disbalance) {
056        super(percentage, maximum);
057        iDisbalance = disbalance;
058    }
059
060    public FractionallyUnbalancedWhenNoExpectations(Double percentage, Double maximum) {
061        this(percentage, maximum, null);
062    }
063
064    public FractionallyUnbalancedWhenNoExpectations(Double percentage) {
065        this(percentage, null, null);
066    }
067
068    public FractionallyUnbalancedWhenNoExpectations() {
069        this(null, null, null);
070    }
071
072    /**
073     * Return allowed disbalance, defaults to 0.1 (parameter OverExpected.Disbalance)
074     * 
075     * @return allowed disbalance
076     */
077    public Double getDisbalance() {
078        return iDisbalance;
079    }
080
081    /**
082     * Is balancing of unlimited sections enabled (parameter General.BalanceUnlimited)
083     * @return true if balancing of unlimited sections is enabled
084     */
085    public boolean isBalanceUnlimited() {
086        return iBalanceUnlimited;
087    }
088
089    /**
090     * Get maximum
091     * @param section given section
092     * @param defaultValue default value (if not set)
093     * @return maximum
094     */
095    public double getMaximum(Section section, double defaultValue) {
096        return getMaximum() == null || getMaximum() <= 0.0 ? defaultValue : getMaximum();
097    }
098
099    @Override
100    public double getOverExpected(Assignment<Request, Enrollment> assignment, Section section, Request request) {
101        Subpart subpart = section.getSubpart();
102
103        if (hasExpectations(subpart) && section.getLimit() > 0)
104            return super.getOverExpected(assignment, section, request);
105
106        if (getDisbalance() == null || getDisbalance() < 0.0)
107            return 0.0;
108
109        double enrlConfig = request.getWeight() + getEnrollment(assignment, subpart.getConfig(), request);
110        int subparts = section.getSubpart().getConfig().getSubparts().size();
111        int limit = getLimit(section);
112        double enrl = request.getWeight() + getEnrollment(assignment, section, request);
113
114        if (limit > 0) {
115            // sections have limits -> desired size is section limit x (total
116            // enrollment / total limit)
117            double desired = (enrlConfig / getLimit(subpart)) * limit;
118            if (enrl - desired >= Math.max(1.0, getDisbalance() * limit)) {
119                double max = getMaximum(section, limit);
120                return Math.min(max, enrl - desired) / (max * subparts);
121            }
122        } else if (isBalanceUnlimited()) {
123            // unlimited sections -> desired size is total enrollment / number
124            // of sections
125            double desired = enrlConfig / subpart.getSections().size();
126            if (enrl - desired >= Math.max(1.0, getDisbalance() * desired)) {
127                double max = getMaximum(section, desired);
128                return Math.min(max, enrl - desired) / (max * subparts);
129            }
130        }
131
132        return 0.0;
133    }
134
135    @Override
136    public String toString() {
137        return "fbal(" + getPercentage() + "," + getMaximum() + "," + getDisbalance() + ")";
138    }
139}