Source code for jmetal.algorithm.singleobjective.evolution_strategy

from copy import copy
from typing import List, TypeVar

from jmetal.core.algorithm import EvolutionaryAlgorithm
from jmetal.core.operator import Mutation
from jmetal.core.problem import Problem
from jmetal.util.constraint_handling import overall_constraint_violation_degree
from jmetal.util.evaluator import Evaluator, SequentialEvaluator
from jmetal.util.generator import Generator, RandomGenerator
from jmetal.util.termination_criterion import TerminationCriterion

S = TypeVar("S")
R = TypeVar("R")

"""
.. module:: evolutionary_algorithm
   :platform: Unix, Windows
   :synopsis: Implementation of Evolutionary Algorithms.

.. moduleauthor:: Antonio J. Nebro <antonio@lcc.uma.es>, Antonio Benítez-Hidalgo <antonio.b@uma.es>
"""



[docs]
class EvolutionStrategy(EvolutionaryAlgorithm[S, R]):
    def __init__(
        self,
        problem: Problem,
        mu: int,
        lambda_: int,
        elitist: bool,
        mutation: Mutation,
        termination_criterion: TerminationCriterion,
        population_generator: Generator = RandomGenerator(),
        population_evaluator: Evaluator = SequentialEvaluator(),
    ):
        super(EvolutionStrategy, self).__init__(problem=problem, population_size=mu, offspring_population_size=lambda_)
        self.mu = mu
        self.lambda_ = lambda_
        self.elitist = elitist

        self.mutation_operator = mutation

        self.population_generator = population_generator
        self.population_evaluator = population_evaluator

        self.termination_criterion = termination_criterion
        self.observable.register(termination_criterion)


[docs]
    def create_initial_solutions(self) -> List[S]:
        return [self.population_generator.new(self.problem) for _ in range(self.population_size)]



[docs]
    def evaluate(self, solution_list: List[S]):
        return self.population_evaluator.evaluate(solution_list, self.problem)



[docs]
    def stopping_condition_is_met(self) -> bool:
        return self.termination_criterion.is_met



[docs]
    def selection(self, population: List[S]) -> List[S]:
        return population



[docs]
    def reproduction(self, population: List[S]) -> List[S]:
        offspring_population = []
        for solution in population:
            for j in range(int(self.lambda_ / self.mu)):
                new_solution = copy(solution)
                offspring_population.append(self.mutation_operator.execute(new_solution))

        return offspring_population



[docs]
    def replacement(self, population: List[S], offspring_population: List[S]) -> List[S]:
        population_pool = []

        if self.elitist:
            population_pool = population
            population_pool.extend(offspring_population)
        else:
            population_pool.extend(offspring_population)

        population_pool.sort(key=lambda s: (overall_constraint_violation_degree(s), s.objectives[0]))

        new_population = []
        for i in range(self.mu):
            new_population.append(population_pool[i])

        return new_population



[docs]
    def result(self) -> R:
        return self.solutions[0]



[docs]
    def get_name(self) -> str:
        return "Elitist evolution Strategy"
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Source code for jmetal.algorithm.singleobjective.evolution_strategy
