Assign students from a given student list to a OptaPlanner studentGroup based on the capacity of a room

Question

I'm new to OptaPlanner and still getting a hang of it. I'm currently going through the OptaPlanner School timetable Use Case. I need to do more tweaking there. Assume I have a list of students, and I want to use Optaplanner to assign those students to studentGroup in Lesson Class based on the capacity of a room.

I have added a capacity attribute to the Room class. since Lesson already has studentGroup variable, I need to assign students to that Lesson who are in the same studentGroup till number of students reaches the Room capacity.

Answer 1

The School Timetabling quickstarts in Timefold/OptaPlanner assigns Lessons to Timeslot+Rooms. It doesn't assign students to lessons. Typically that's done earlier in the real world (tactical vs operation planning).

If the student for each lesson is already fixed, you can do a constraint like this:

.forEach(Lesson.class)
.filter(lesson -> lesson.getRoom().getCapacity() < lesson.getStudentSize())
.penalize(..., lesson -> lesson.getRoom().getCapacity() - lesson.getStudentSize())

And that would be it.

However, if the students can still switch lessons, it's get a lot more complicated (2 planning entities: StudentAssignment (1 planning variable Lesson) and Lesson (2 planning variables room and timeslot) and you probably need custom moves etc for it to solve efficiently.