tsp.py

#    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 array
import random
import json

import numpy

from deap import algorithms
from deap import base
from deap import creator
from deap import tools

# gr*.json contains the distance map in list of list style in JSON format
# Optimal solutions are : gr17 = 2085, gr24 = 1272, gr120 = 6942
with open("tsp/gr17.json", "r") as tsp_data:
    tsp = json.load(tsp_data)

distance_map = tsp["DistanceMatrix"]
IND_SIZE = tsp["TourSize"]

creator.create("FitnessMin", base.Fitness, weights=(-1.0,))
creator.create("Individual", array.array, typecode='i', fitness=creator.FitnessMin)

toolbox = base.Toolbox()

# Attribute generator
toolbox.register("indices", random.sample, range(IND_SIZE), IND_SIZE)

# Structure initializers
toolbox.register("individual", tools.initIterate, creator.Individual, toolbox.indices)
toolbox.register("population", tools.initRepeat, list, toolbox.individual)

def evalTSP(individual):
    distance = distance_map[individual[-1]][individual[0]]
    for gene1, gene2 in zip(individual[0:-1], individual[1:]):
        distance += distance_map[gene1][gene2]
    return distance,

toolbox.register("mate", tools.cxPartialyMatched)
toolbox.register("mutate", tools.mutShuffleIndexes, indpb=0.05)
toolbox.register("select", tools.selTournament, tournsize=3)
toolbox.register("evaluate", evalTSP)

def main():
    random.seed(169)

    pop = toolbox.population(n=300)

    hof = tools.HallOfFame(1)
    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, 0.7, 0.2, 40, stats=stats, 
                        halloffame=hof)

    return pop, stats, hof

if __name__ == "__main__":
    main()