Segmentation fault when computing hypervolume with single objective (n_obj = 1) in pymoo

[umeshnandargi]

Hello all,
I’m encountering a segmentation fault (core dumped) when computing hypervolume using pymoo, specifically when the problem has only one objective (n_obj = 1).
I’m using a custom callback to compute hypervolume during optimization:

    class HVCallback(Callback):

    def __init__(self, ref_point=np.array([0.0, 0.0])):
        super().__init__()
        self.hv = HV(ref_point=ref_point)
        self.data["hv"] = []

    def notify(self, algorithm):
        F = algorithm.pop.get("F")

        # Remove infeasible solutions if constraints exist
        if algorithm.problem.n_constr > 0:
            feas = algorithm.pop.get("feasible")
            F = F[feas]

        if len(F) > 0:
            hv_value = self.hv.do(F)   # <-- segmentation fault occurs here
        else:
            hv_value = 0

        self.data["hv"].append(hv_value)

I cannot debug further but here is the last output that I got :

==========================================================
n_gen  |  n_eval  | n_nds  |      eps      |   indicator  
==========================================================
     1 |       50 |      1 |             - |             -
Segmentation fault (core dumped)

is it because the problem is no longer a multi objective optimization when n_obj = 1 ?

[tpgillam]

My guess is that this is:

• Segmentation fault on python:3.12 multi-objective/moocore#58

the issue is resolved, but there hasn't been a new moocore release yet containing the fix.

@MLopez-Ibanez would you be open to tagging a new moocore release soon?

[umeshnandargi]

Thanks for the reply and letting me know, will wait for the release.

[MLopez-Ibanez]

Yes, I will make a release within a month, probably earlier, but it would actually help a lot if you would test it.

You can install the development version (which is free of bugs as far as I know) following this: https://github.com/multi-objective/moocore/tree/main/python#install

We provide wheels, so installation should be painless.

[umeshnandargi]

Tested with

Name: moocore
Version: 0.3.0.dev0

and it is working perfectly with one objective. Thanks a lot for your help!! @MLopez-Ibanez @tpgillam