Optaplanner 8 - 学校时间表 constraintFactory 避免在同一天出现较早的空时隙

Question

我正在学习 Optaplanner，如果涉及课程，我在创建新约束方面取得了巨大成功。但是，如果没有分配给时间段的课程，我正在努力弄清楚如何创建 constraintFactory。

我会从早上开始补课，如果可能的话，我会用 .reward("no empty earlier time slots", HardSoftScore.ONE_SOFT)。类似于：

import org.acme.kotlin.schooltimetabling.domain.Timeslot

...

    fun noEmptyEarlierTimeslots(constraintFactory: ConstraintFactory): Constraint {
        // try to fill the slots from the start and have not empty slots later in the day on the same day
        return constraintFactory
                .from(Timeslot::class.java)
                .join(Timeslot::class.java)
                .filter { slot1: Timeslot, slot2: Timeslot -> slot1.startTime.toLocalDate() === slot2.startTime.toLocalDate() }
                    slot1.startTime < slo2.startTime && ifNotExists(slot1::Lesson) && ifExists(slot2::Lesson)
                .reward("no empty earlier time slots", HardSoftScore.ONE_SOFT)
    }

[我将 startTime 和 endTime 更改为 localDateTime - 因此 toLocalDate() ]

任何帮助将不胜感激。

Answer 1

"if there is no lesson assigned to a timeslot."

我认为 .ifNotExists() 可能适用于此。基本上类似于 from(Timeslot.class).ifNotExists(Lesson.class, equal(identity(), Lesson::getTimeslot)...

"I would fill lessons from the morning and have not empty slots if possible"

看看示例中的这个约束：

Constraint teacherTimeEfficiency(ConstraintFactory constraintFactory) {
    // A teacher prefers to teach sequential lessons and dislikes gaps between lessons.
    return constraintFactory
            .from(Lesson.class)
            .join(Lesson.class, Joiners.equal(Lesson::getTeacher),
                    Joiners.equal((lesson) -> lesson.getTimeslot().getDayOfWeek()))
            .filter((lesson1, lesson2) -> {
                Duration between = Duration.between(lesson1.getTimeslot().getEndTime(),
                        lesson2.getTimeslot().getStartTime());
                return !between.isNegative() && between.compareTo(Duration.ofMinutes(30)) <= 0;
            })
            .reward("Teacher time efficiency", HardSoftScore.ONE_SOFT);
}

Optaplanner 8 - 学校时间表 constraintFactory 避免在同一天出现较早的空时隙

Optaplanner 8 - School timetabling constraintFactory avoid earlier empty timeslots in the same day

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