dlmo-model / pareto.py

import minizinc


def pareto_front(instance, objectives):
    front = []
    result = None
    with instance.branch() as instance:
        failed = False
        while not failed:
            result = instance.solve()
            # print(result)
            # print("----------------------------------------")
            if result == None or result.status == minizinc.Status.UNSATISFIABLE:
                failed = True
            else:
                to_remove = []
                for i in range(len(front)):
                    if all([result[o] <= front[i][o] for o in objectives]):
                        to_remove.append(i)
                # print(to_remove[::-1])
                for r in to_remove[::-1]:
                    front.pop(r)
                instance.add_string(
                    "constraint "
                    + " \/ ".join([f"{o} < {result[o]}" for o in objectives])
                    + ";\n"
                )
                front.append(result)
    return front


if __name__ == "__main__":
    inst = minizinc.Instance(
        minizinc.Solver.lookup("gurobi"), minizinc.Model("dlmo.mzn")
    )
    inst.add_file("full.dzn")
    inst.add_file("sri.dzn")

    front = pareto_front(inst, ["total_samples", "total_not_detected"])
    front = sorted(front, key=lambda sol: sol["num_samples"])

    for sol in front:
        print(
            ",".join(
                [
                    str(sol["first_sample"]),
                    str(sol["num_samples"]),
                    str(sol["total_samples"]),
                    str(sol["num_patients"] - sol["total_not_detected"]),
                    str(sol["num_before"]),
                    str(sol["num_after"]),
                ]
            )
        )
    print("----------------------------------------------------")
    for sol in front:
        print(sol)