Preference point-based NSGA-II

Example

from jmetal.algorithm.multiobjective.nsgaii import NSGAII
from jmetal.operator import SBXCrossover, PolynomialMutation
from jmetal.problem import ZDT2
from jmetal.util.comparator import GDominanceComparator
from jmetal.util.termination_criterion import StoppingByEvaluations

problem = ZDT2()

max_evaluations = 25000
reference_point = [0.2, 0.5]

algorithm = NSGAII(
    problem=problem,
    population_size=100,
    offspring_population_size=100,
    mutation=PolynomialMutation(probability=1.0 / problem.number_of_variables, distribution_index=20),
    crossover=SBXCrossover(probability=1.0, distribution_index=20),
    dominance_comparator=GDominanceComparator(reference_point),
    termination_criterion=StoppingByEvaluations(max=max_evaluations)
)

algorithm.run()
solutions = algorithm.get_result()

We can now visualize the Pareto front approximation:

from jmetal.lab.visualization.plotting import Plot
from jmetal.util.solution import get_non_dominated_solutions

front = get_non_dominated_solutions(solutions)

plot_front = Plot(plot_title='Pareto front approximation', axis_labels=['x', 'y'], reference_point=reference_point)
plot_front.plot(front, label='gNSGAII-ZDT1')

API

class jmetal.algorithm.multiobjective.nsgaii.DynamicNSGAII(problem: jmetal.core.problem.DynamicProblem[~S][S], population_size: int, offspring_population_size: int, mutation: jmetal.core.operator.Mutation, crossover: jmetal.core.operator.Crossover, selection: jmetal.core.operator.Selection = <jmetal.operator.selection.BinaryTournamentSelection object>, termination_criterion: jmetal.util.termination_criterion.TerminationCriterion = <jmetal.util.termination_criterion.StoppingByEvaluations object>, population_generator: Generator = <jmetal.util.generator.RandomGenerator object>, population_evaluator: jmetal.util.evaluator.Evaluator = <jmetal.util.evaluator.SequentialEvaluator object>, dominance_comparator: jmetal.util.comparator.DominanceComparator = <jmetal.util.comparator.DominanceComparator object>)

Bases: jmetal.algorithm.multiobjective.nsgaii.NSGAII, jmetal.core.algorithm.DynamicAlgorithm

restart()

stopping_condition_is_met()

The stopping condition is met or not.

update_progress()

Update the progress after each iteration.