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OptaPlanner solves planning problems.
This lightweight, embeddable planning engine implements powerful and scalable algorithms
to optimize business resource scheduling and planning.
This module contains the examples which demonstrate how to use it in a normal Java application.
/*
* Copyright 2020 Red Hat, Inc. and/or its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.optaplanner.examples.examination.solver.score;
import static org.optaplanner.core.api.score.stream.ConstraintCollectors.sum;
import static org.optaplanner.core.api.score.stream.Joiners.equal;
import static org.optaplanner.core.api.score.stream.Joiners.filtering;
import static org.optaplanner.core.api.score.stream.Joiners.greaterThan;
import static org.optaplanner.core.api.score.stream.Joiners.lessThan;
import static org.optaplanner.core.api.score.stream.Joiners.lessThanOrEqual;
import java.util.function.Function;
import org.optaplanner.core.api.score.stream.Constraint;
import org.optaplanner.core.api.score.stream.ConstraintFactory;
import org.optaplanner.core.api.score.stream.ConstraintProvider;
import org.optaplanner.examples.examination.domain.Exam;
import org.optaplanner.examples.examination.domain.ExaminationConstraintConfiguration;
import org.optaplanner.examples.examination.domain.Period;
import org.optaplanner.examples.examination.domain.PeriodPenalty;
import org.optaplanner.examples.examination.domain.PeriodPenaltyType;
import org.optaplanner.examples.examination.domain.Room;
import org.optaplanner.examples.examination.domain.RoomPenalty;
import org.optaplanner.examples.examination.domain.RoomPenaltyType;
import org.optaplanner.examples.examination.domain.solver.TopicConflict;
// TODO The ExaminationConstraintProvider is unusually slow. For more information, see: https://issues.redhat.com/browse/PLANNER-2011
public class ExaminationConstraintProvider implements ConstraintProvider {
@Override
public Constraint[] defineConstraints(ConstraintFactory constraintFactory) {
return new Constraint[] {
// Hard constraints
conflictingExamsInSamePeriod(constraintFactory),
periodDurationTooShort(constraintFactory),
roomCapacityTooSmall(constraintFactory),
periodPenaltyExamCoincidence(constraintFactory),
periodPenaltyExclusion(constraintFactory),
periodPenaltyAfter(constraintFactory),
roomPenaltyExclusive(constraintFactory),
// Soft constraints
twoExamsInARow(constraintFactory),
twoExamsInADay(constraintFactory),
periodSpread(constraintFactory),
mixedDurations(constraintFactory),
frontLoad(constraintFactory),
periodPenalty(constraintFactory),
roomPenalty(constraintFactory)
};
}
protected Constraint conflictingExamsInSamePeriod(ConstraintFactory constraintFactory) {
return constraintFactory.from(TopicConflict.class)
.join(Exam.class,
equal(TopicConflict::getLeftTopic, Exam::getTopic),
filtering((topicConflict, leftExam) -> leftExam.getPeriod() != null))
.ifExists(Exam.class,
equal((topicConflict, leftExam) -> topicConflict.getRightTopic(), Exam::getTopic),
equal((topicConflict, leftExam) -> leftExam.getPeriod(), Exam::getPeriod))
.penalizeConfigurable("conflictingExamsInSamePeriod",
(topicConflict, leftExam) -> topicConflict.getStudentSize());
}
protected Constraint periodDurationTooShort(ConstraintFactory constraintFactory) {
return constraintFactory.from(Exam.class)
.filter(exam -> exam.getTopicDuration() > exam.getPeriodDuration())
.penalizeConfigurable("periodDurationTooShort", Exam::getTopicStudentSize);
}
protected Constraint roomCapacityTooSmall(ConstraintFactory constraintFactory) {
return constraintFactory.from(Exam.class)
// Period is genuine planning variable on LeadingExam, shadow var on FollowingExam, nothing on Exam.
.filter(exam -> exam.getPeriod() != null)
.groupBy(Exam::getRoom, Exam::getPeriod, sum(Exam::getTopicStudentSize))
.filter((room, period, totalStudentSize) -> totalStudentSize > room.getCapacity())
.penalizeConfigurable("roomCapacityTooSmall",
(room, period, totalStudentSize) -> totalStudentSize - room.getCapacity());
}
protected Constraint periodPenaltyExamCoincidence(ConstraintFactory constraintFactory) {
return constraintFactory.from(PeriodPenalty.class)
.filter(periodPenalty -> periodPenalty.getPeriodPenaltyType() == PeriodPenaltyType.EXAM_COINCIDENCE)
.join(Exam.class,
equal(PeriodPenalty::getLeftTopic, Exam::getTopic),
filtering((periodPenalty, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((periodPenalty, leftExam) -> periodPenalty.getRightTopic(), Exam::getTopic),
filtering((periodPenalty, leftExam, rightExam) -> rightExam.getPeriod() != null),
filtering((periodPenalty, leftExam, rightExam) -> leftExam.getPeriod() != rightExam.getPeriod()))
.penalizeConfigurable("periodPenaltyExamCoincidence",
(periodPenalty, leftExam, rightExam) -> leftExam.getTopic().getStudentSize()
+ rightExam.getTopic().getStudentSize());
}
protected Constraint periodPenaltyExclusion(ConstraintFactory constraintFactory) {
return constraintFactory.from(PeriodPenalty.class)
.filter(periodPenalty -> periodPenalty.getPeriodPenaltyType() == PeriodPenaltyType.EXCLUSION)
.join(Exam.class,
equal(PeriodPenalty::getLeftTopic, Exam::getTopic),
filtering((periodPenalty, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((periodPenalty, leftExam) -> periodPenalty.getRightTopic(), Exam::getTopic),
equal((periodPenalty, leftExam) -> leftExam.getPeriod(), Exam::getPeriod))
.penalizeConfigurable("periodPenaltyExclusion",
(periodPenalty, leftExam, rightExam) -> leftExam.getTopic().getStudentSize()
+ rightExam.getTopic().getStudentSize());
}
protected Constraint periodPenaltyAfter(ConstraintFactory constraintFactory) {
return constraintFactory.from(PeriodPenalty.class)
.filter(periodPenalty -> periodPenalty.getPeriodPenaltyType() == PeriodPenaltyType.AFTER)
.join(Exam.class,
equal(PeriodPenalty::getLeftTopic, Exam::getTopic),
filtering((periodPenalty, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((periodPenalty, leftExam) -> periodPenalty.getRightTopic(), Exam::getTopic),
lessThanOrEqual((periodPenalty, leftExam) -> leftExam.getPeriodIndex(), Exam::getPeriodIndex))
.penalizeConfigurable("periodPenaltyAfter",
(periodPenalty, leftExam, rightExam) -> leftExam.getTopic().getStudentSize()
+ rightExam.getTopic().getStudentSize());
}
protected Constraint roomPenaltyExclusive(ConstraintFactory constraintFactory) {
return constraintFactory.from(RoomPenalty.class)
.filter(roomPenalty -> roomPenalty.getRoomPenaltyType() == RoomPenaltyType.ROOM_EXCLUSIVE)
.join(Exam.class,
equal(RoomPenalty::getTopic, Exam::getTopic),
filtering((roomPenalty, leftExam) -> leftExam.getPeriod() != null && leftExam.getRoom() != null))
.join(Exam.class,
equal((roomPenalty, leftExam) -> leftExam.getRoom(), Exam::getRoom),
equal((roomPenalty, leftExam) -> leftExam.getPeriod(), Exam::getPeriod),
filtering((roomPenalty, leftExam, rightExam) -> leftExam.getTopic() != rightExam.getTopic()))
.penalizeConfigurable("roomPenaltyExclusive",
(periodPenalty, leftExam, rightExam) -> leftExam.getTopic().getStudentSize()
+ rightExam.getTopic().getStudentSize());
}
protected Constraint twoExamsInARow(ConstraintFactory constraintFactory) {
return constraintFactory.from(TopicConflict.class)
.join(Exam.class,
equal(TopicConflict::getLeftTopic, Exam::getTopic),
filtering((topicConflict, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((topicConflict, leftExam) -> topicConflict.getRightTopic(), Exam::getTopic),
equal((topicConflict, leftExam) -> leftExam.getDayIndex(), Exam::getDayIndex),
filtering((topicConflict, leftExam,
rightExam) -> getPeriodIndexDifferenceBetweenExams(leftExam, rightExam) == 1))
.penalizeConfigurable("twoExamsInARow", (topicConflict, leftExam, rightExam) -> topicConflict.getStudentSize());
}
protected Constraint twoExamsInADay(ConstraintFactory constraintFactory) {
return constraintFactory.from(TopicConflict.class)
.join(Exam.class,
equal(TopicConflict::getLeftTopic, Exam::getTopic),
filtering((topicConflict, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((topicConflict, leftExam) -> topicConflict.getRightTopic(), Exam::getTopic),
equal((topicConflict, leftExam) -> leftExam.getDayIndex(), Exam::getDayIndex),
// Find exams in a day, but not being held right after each other. That case is handled in the twoExamsInARow constraint.
filtering((topicConflict, leftExam,
rightExam) -> getPeriodIndexDifferenceBetweenExams(leftExam, rightExam) > 1))
.penalizeConfigurable("twoExamsInADay", (topicConflict, leftExam, rightExam) -> topicConflict.getStudentSize());
}
protected Constraint periodSpread(ConstraintFactory constraintFactory) {
return constraintFactory.from(ExaminationConstraintConfiguration.class)
.join(TopicConflict.class)
.join(Exam.class,
equal((config, topicConflict) -> topicConflict.getLeftTopic(), Exam::getTopic),
filtering((config, topicConflict, leftExam) -> leftExam.getPeriod() != null))
.join(Exam.class,
equal((config, topicConflict, leftExam) -> topicConflict.getRightTopic(), Exam::getTopic),
filtering((config, topicConflict, leftExam, rightExam) -> rightExam.getPeriod() != null),
filtering((config, topicConflict, leftExam,
rightExam) -> getPeriodIndexDifferenceBetweenExams(leftExam,
rightExam) < (config.getPeriodSpreadLength() + 1)))
.penalizeConfigurable("periodSpread",
(config, topicConflict, leftExam, rightExam) -> topicConflict.getStudentSize());
}
protected Constraint mixedDurations(ConstraintFactory constraintFactory) {
// 4 mixed durations of 100, 150, 200 and 200 should only result in 2 penalties (for 100&150 and 100&200).
return constraintFactory.from(Exam.class)
// Period is genuine planning variable on LeadingExam, shadow var on FollowingExam, nothing on Exam.
.filter(leftExam -> leftExam.getPeriod() != null)
.ifNotExistsOther(Exam.class,
equal(Exam::getPeriod),
equal(Exam::getRoom),
greaterThan(Exam::getId))
.join(Exam.class,
equal(Exam::getPeriod),
equal(Exam::getRoom),
lessThan(Exam::getId),
filtering((leftExam, rightExam) -> leftExam.getTopicDuration() != rightExam.getTopicDuration()))
.ifNotExists(Exam.class,
equal((leftExam, rightExam) -> leftExam.getPeriod(), Exam::getPeriod),
equal((leftExam, rightExam) -> leftExam.getRoom(), Exam::getRoom),
equal((leftExam, rightExam) -> rightExam.getTopicDuration(), Exam::getTopicDuration),
greaterThan((leftExam, rightExam) -> rightExam.getId(), Exam::getId))
.penalizeConfigurable("mixedDurations");
}
protected Constraint frontLoad(ConstraintFactory constraintFactory) {
return constraintFactory.from(Exam.class)
.filter(exam -> exam.isTopicFrontLoadLarge() && exam.isPeriodFrontLoadLast())
.penalizeConfigurable("frontLoad");
}
protected Constraint periodPenalty(ConstraintFactory constraintFactory) {
return constraintFactory.from(Period.class)
.filter(period -> period.getPenalty() != 0)
.join(Exam.class,
equal(Function.identity(), Exam::getPeriod))
.penalizeConfigurable("periodPenalty", (period, exam) -> period.getPenalty());
}
protected Constraint roomPenalty(ConstraintFactory constraintFactory) {
return constraintFactory.from(Room.class)
.filter(room -> room.getPenalty() != 0)
.join(Exam.class,
equal(Function.identity(), Exam::getRoom))
.penalizeConfigurable("roomPenalty", (room, exam) -> room.getPenalty());
}
private int getPeriodIndexDifferenceBetweenExams(Exam leftExam, Exam rightExam) {
return Math.abs(leftExam.getPeriodIndex() - rightExam.getPeriodIndex());
}
}