nonlinear_constraints.py

import pygmo as pg

class TestProblem:

    def fitness(self, x):
        param_1 = x[0]
        param_2 = x[1]

        metric_1 = 2 * param_1
        metric_2 = 2 * param_2

        constraint_1 = -0.5  # param_1 - 5

        return [metric_1, metric_2, constraint_1]  # , constraint_1, constraint_2]

    def get_nic(self):
        return 1

    def get_nobj(self):
        return 2

    def get_bounds(self):
        return [-1, -1], [1, 1]


if __name__ == '__main__':
    algorithm = pg.algorithm(pg.nspso())

    problem = pg.problem(TestProblem())

    print(problem)

    population = pg.population(problem, size=50)

    population = algorithm.evolve(population)

    fits, vectors = population.get_f(), population.get_x()

    ndf, dl, dc, ndr = pg.fast_non_dominated_sorting(fits)

    print(ndf)

when i use pygmo to deal with muti-label problem, it will meet "Non linear constraints detected" error, if I add Equality or Inequality constraints. I see your code meet the same paroblem, what did you do about this bug?