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# This file is part of DEAP.
#
# DEAP is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as
# published by the Free Software Foundation, either version 3 of
# the License, or (at your option) any later version.
#
# DEAP is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with DEAP. If not, see <http://www.gnu.org/licenses/>.
import random
import numpy
from deap import algorithms
from deap import base
from deap import creator
from deap import tools
creator.create("FitnessMax", base.Fitness, weights=(1.0,))
creator.create("Individual", numpy.ndarray, fitness=creator.FitnessMax)
toolbox = base.Toolbox()
toolbox.register("attr_bool", random.randint, 0, 1)
toolbox.register("individual", tools.initRepeat, creator.Individual, toolbox.attr_bool, n=100)
toolbox.register("population", tools.initRepeat, list, toolbox.individual)
def evalOneMax(individual):
return sum(individual),
def cxTwoPointCopy(ind1, ind2):
"""Execute a two points crossover with copy on the input individuals. The
copy is required because the slicing in numpy returns a view of the data,
which leads to a self overwritting in the swap operation. It prevents
::
>>> import numpy
>>> a = numpy.array((1,2,3,4))
>>> b = numpy.array((5.6.7.8))
>>> a[1:3], b[1:3] = b[1:3], a[1:3]
>>> print(a)
[1 6 7 4]
>>> print(b)
[5 6 7 8]
"""
size = len(ind1)
cxpoint1 = random.randint(1, size)
cxpoint2 = random.randint(1, size - 1)
if cxpoint2 >= cxpoint1:
cxpoint2 += 1
else: # Swap the two cx points
cxpoint1, cxpoint2 = cxpoint2, cxpoint1
ind1[cxpoint1:cxpoint2], ind2[cxpoint1:cxpoint2] \
= ind2[cxpoint1:cxpoint2].copy(), ind1[cxpoint1:cxpoint2].copy()
return ind1, ind2
toolbox.register("evaluate", evalOneMax)
toolbox.register("mate", cxTwoPointCopy)
toolbox.register("mutate", tools.mutFlipBit, indpb=0.05)
toolbox.register("select", tools.selTournament, tournsize=3)
def main():
random.seed(64)
pop = toolbox.population(n=300)
# Numpy equality function (operators.eq) between two arrays returns the
# equality element wise, which raises an exception in the if similar()
# check of the hall of fame. Using a different equality function like
# numpy.array_equal or numpy.allclose solve this issue.
hof = tools.HallOfFame(1, similar=numpy.array_equal)
stats = tools.Statistics(lambda ind: ind.fitness.values)
stats.register("avg", numpy.mean)
stats.register("std", numpy.std)
stats.register("min", numpy.min)
stats.register("max", numpy.max)
algorithms.eaSimple(pop, toolbox, cxpb=0.5, mutpb=0.2, ngen=40, stats=stats,
halloffame=hof)
return pop, stats, hof
if __name__ == "__main__":
main()
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