def eaGenerateUpdate(toolbox, ngen, halloffame=None, stats=None,
verbose=__debug__):
"""This is algorithm implements the ask-tell model proposed in
[Colette2010]_, where ask is called `generate` and tell is called `update`.
:param toolbox: A :class:`~deap.base.Toolbox` that contains the evolution
operators.
:param ngen: The number of generation.
:param stats: A :class:`~deap.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~deap.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population
:returns: A class:`~deap.tools.Logbook` with the statistics of the
evolution
The algorithm generates the individuals using the :func:`toolbox.generate`
function and updates the generation method with the :func:`toolbox.update`
function. It returns the optimized population and a
:class:`~deap.tools.Logbook` with the statistics of the evolution. The
logbook will contain the generation number, the number of evalutions for
each generation and the statistics if a :class:`~deap.tools.Statistics` is
given as argument. The pseudocode goes as follow ::
for g in range(ngen):
population = toolbox.generate()
evaluate(population)
toolbox.update(population)
.. [Colette2010] Collette, Y., N. Hansen, G. Pujol, D. Salazar Aponte and
R. Le Riche (2010). On Object-Oriented Programming of Optimizers -
Examples in Scilab. In P. Breitkopf and R. F. Coelho, eds.:
Multidisciplinary Design Optimization in Computational Mechanics,
Wiley, pp. 527-565;
"""
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
for gen in xrange(ngen):
# Generate a new population
population = toolbox.generate()
# Evaluate the individuals
fitnesses = toolbox.map(toolbox.evaluate, population)
for ind, fit in zip(population, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
# Update the strategy with the evaluated individuals
toolbox.update(population)
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=gen, nevals=len(population), **record)
if verbose:
print logbook.stream
return population, logbook
def test_pickle_logbook(self):
stats = tools.Statistics()
logbook = tools.Logbook()
stats.register("mean", numpy.mean)
record = stats.compile([1,2,3,4,5,6,8,9,10])
logbook.record(**record)
stats_s = pickle.dumps(logbook)
logbook_r = pickle.loads(stats_s)
self.assertEqual(logbook, logbook_r, "Unpickled logbook != pickled logbook")
def eaMuCommaLambda(population,
toolbox,
mu,
lambda_,
cxpb,
mutpb,
ngen,
stats=None,
halloffame=None,
verbose=__debug__):
assert lambda_ >= mu, "lambda must be greater or equal to mu."
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
for gen in range(1, ngen + 1):
offspring = varOr(population, toolbox, lambda_, cxpb, mutpb)
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(offspring)
population[:] = toolbox.select(offspring, mu)
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook
def eaGenerateUpdate(toolbox,
ngen,
halloffame=None,
stats=None,
verbose=__debug__):
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
for gen in xrange(ngen):
population = toolbox.generate()
fitnesses = toolbox.map(toolbox.evaluate, population)
for ind, fit in zip(population, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
toolbox.update(population)
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=gen, nevals=len(population), **record)
if verbose:
print logbook.stream
return population, logbook
def eaSimple(population, toolbox, cxpb, mutpb, ngen, stats=None,
halloffame=None, verbose=__debug__):
"""This algorithm reproduce the simplest evolutionary algorithm as
presented in chapter 7 of [Back2000]_.
:param population: A list of individuals.
:param toolbox: A :class:`~deap.base.Toolbox` that contains the evolution
operators.
:param cxpb: The probability of mating two individuals.
:param mutpb: The probability of mutating an individual.
:param ngen: The number of generation.
:param stats: A :class:`~deap.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~deap.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population
:returns: A class:`~deap.tools.Logbook` with the statistics of the
evolution
The algorithm takes in a population and evolves it in place using the
:meth:`varAnd` method. It returns the optimized population and a
:class:`~deap.tools.Logbook` with the statistics of the evolution. The
logbook will contain the generation number, the number of evalutions for
each generation and the statistics if a :class:`~deap.tools.Statistics` is
given as argument. The *cxpb* and *mutpb* arguments are passed to the
:func:`varAnd` function. The pseudocode goes as follow ::
evaluate(population)
for g in range(ngen):
population = select(population, len(population))
offspring = varAnd(population, toolbox, cxpb, mutpb)
evaluate(offspring)
population = offspring
As stated in the pseudocode above, the algorithm goes as follow. First, it
evaluates the individuals with an invalid fitness. Second, it enters the
generational loop where the selection procedure is applied to entirely
replace the parental population. The 1:1 replacement ratio of this
algorithm **requires** the selection procedure to be stochastic and to
select multiple times the same individual, for example,
:func:`~deap.tools.selTournament` and :func:`~deap.tools.selRoulette`.
Third, it applies the :func:`varAnd` function to produce the next
generation population. Fourth, it evaluates the new individuals and
compute the statistics on this population. Finally, when *ngen*
generations are done, the algorithm returns a tuple with the final
population and a :class:`~deap.tools.Logbook` of the evolution.
.. note::
Using a non-stochastic selection method will result in no selection as
the operator selects *n* individuals from a pool of *n*.
This function expects the :meth:`toolbox.mate`, :meth:`toolbox.mutate`,
:meth:`toolbox.select` and :meth:`toolbox.evaluate` aliases to be
registered in the toolbox.
.. [Back2000] Back, Fogel and Michalewicz, "Evolutionary Computation 1 :
Basic Algorithms and Operators", 2000.
"""
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
record = stats.compile(population) if stats else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
# Begin the generational process
for gen in range(1, ngen + 1):
# Select the next generation individuals
offspring = toolbox.select(population, len(population))
# Vary the pool of individuals
offspring = varAnd(offspring, toolbox, cxpb, mutpb)
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
# Update the hall of fame with the generated individuals
if halloffame is not None:
halloffame.update(offspring)
# Replace the current population by the offspring
population[:] = offspring
# Append the current generation statistics to the logbook
record = stats.compile(population) if stats else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook
def eaMuCommaLambda(population, toolbox, mu, lambda_, cxpb, mutpb, ngen,
stats=None, halloffame=None, verbose=__debug__):
"""This is the :math:`(\mu~,~\lambda)` evolutionary algorithm.
:param population: A list of individuals.
:param toolbox: A :class:`~deap.base.Toolbox` that contains the evolution
operators.
:param mu: The number of individuals to select for the next generation.
:param lambda\_: The number of children to produce at each generation.
:param cxpb: The probability that an offspring is produced by crossover.
:param mutpb: The probability that an offspring is produced by mutation.
:param ngen: The number of generation.
:param stats: A :class:`~deap.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~deap.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population
:returns: A class:`~deap.tools.Logbook` with the statistics of the
evolution
The algorithm takes in a population and evolves it in place using the
:func:`varOr` function. It returns the optimized population and a
:class:`~deap.tools.Logbook` with the statistics of the evolution. The
logbook will contain the generation number, the number of evalutions for
each generation and the statistics if a :class:`~deap.tools.Statistics` is
given as argument. The *cxpb* and *mutpb* arguments are passed to the
:func:`varOr` function. The pseudocode goes as follow ::
evaluate(population)
for g in range(ngen):
offspring = varOr(population, toolbox, lambda_, cxpb, mutpb)
evaluate(offspring)
population = select(offspring, mu)
First, the individuals having an invalid fitness are evaluated. Second,
the evolutionary loop begins by producing *lambda_* offspring from the
population, the offspring are generated by the :func:`varOr` function. The
offspring are then evaluated and the next generation population is
selected from **only** the offspring. Finally, when
*ngen* generations are done, the algorithm returns a tuple with the final
population and a :class:`~deap.tools.Logbook` of the evolution.
.. note::
Care must be taken when the lambda:mu ratio is 1 to 1 as a
non-stochastic selection will result in no selection at all as the
operator selects *lambda* individuals from a pool of *mu*.
This function expects :meth:`toolbox.mate`, :meth:`toolbox.mutate`,
:meth:`toolbox.select` and :meth:`toolbox.evaluate` aliases to be
registered in the toolbox. This algorithm uses the :func:`varOr`
variation.
"""
assert lambda_ >= mu, "lambda must be greater or equal to mu."
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
# Begin the generational process
for gen in range(1, ngen + 1):
# Vary the population
offspring = varOr(population, toolbox, lambda_, cxpb, mutpb)
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
# Update the hall of fame with the generated individuals
if halloffame is not None:
halloffame.update(offspring)
# Select the next generation population
population[:] = toolbox.select(offspring, mu)
# Update the statistics with the new population
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook
def harm(population,
toolbox,
cxpb,
mutpb,
ngen,
alpha,
beta,
gamma,
rho,
nbrindsmodel=-1,
mincutoff=20,
stats=None,
halloffame=None,
verbose=__debug__):
"""Implement bloat control on a GP evolution using HARM-GP, as defined in
[Gardner2015]. It is implemented in the form of an evolution algorithm
(similar to :func:`~deap.algorithms.eaSimple`).
:param population: A list of individuals.
:param toolbox: A :class:`~deap.base.Toolbox` that contains the evolution
operators.
:param cxpb: The probability of mating two individuals.
:param mutpb: The probability of mutating an individual.
:param ngen: The number of generation.
:param alpha: The HARM *alpha* parameter.
:param beta: The HARM *beta* parameter.
:param gamma: The HARM *gamma* parameter.
:param rho: The HARM *rho* parameter.
:param nbrindsmodel: The number of individuals to generate in order to
model the natural distribution. -1 is a special
value which uses the equation proposed in
[Gardner2015] to set the value of this parameter :
max(2000, len(population))
:param mincutoff: The absolute minimum value for the cutoff point. It is
used to ensure that HARM does not shrink the population
too much at the beginning of the evolution. The default
value is usually fine.
:param stats: A :class:`~deap.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~deap.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population
:returns: A class:`~deap.tools.Logbook` with the statistics of the
evolution
This function expects the :meth:`toolbox.mate`, :meth:`toolbox.mutate`,
:meth:`toolbox.select` and :meth:`toolbox.evaluate` aliases to be
registered in the toolbox.
.. note::
The recommended values for the HARM-GP parameters are *alpha=0.05*,
*beta=10*, *gamma=0.25*, *rho=0.9*. However, these parameters can be
adjusted to perform better on a specific problem (see the relevant
paper for tuning information). The number of individuals used to
model the natural distribution and the minimum cutoff point are less
important, their default value being effective in most cases.
.. [Gardner2015] M.-A. Gardner, C. Gagne, and M. Parizeau, Controlling
Code Growth by Dynamically Shaping the Genotype Size Distribution,
Genetic Programming and Evolvable Machines, 2015,
DOI 10.1007/s10710-015-9242-8
"""
def _genpop(n, pickfrom=[], acceptfunc=lambda s: True, producesizes=False):
# Generate a population of n individuals, using individuals in
# *pickfrom* if possible, with a *acceptfunc* acceptance function.
# If *producesizes* is true, also return a list of the produced
# individuals sizes.
# This function is used 1) to generate the natural distribution
# (in this case, pickfrom and acceptfunc should be let at their
# default values) and 2) to generate the final population, in which
# case pickfrom should be the natural population previously generated
# and acceptfunc a function implementing the HARM-GP algorithm.
producedpop = []
producedpopsizes = []
while len(producedpop) < n:
if len(pickfrom) > 0:
# If possible, use the already generated
# individuals (more efficient)
aspirant = pickfrom.pop()
if acceptfunc(len(aspirant)):
producedpop.append(aspirant)
if producesizes:
producedpopsizes.append(len(aspirant))
else:
opRandom = random.random()
if opRandom < cxpb:
# Crossover
aspirant1, aspirant2 = toolbox.mate(
*map(toolbox.clone, toolbox.select(population, 2)))
del aspirant1.fitness.values, aspirant2.fitness.values
if acceptfunc(len(aspirant1)):
producedpop.append(aspirant1)
if producesizes:
producedpopsizes.append(len(aspirant1))
if len(producedpop) < n and acceptfunc(len(aspirant2)):
producedpop.append(aspirant2)
if producesizes:
producedpopsizes.append(len(aspirant2))
else:
aspirant = toolbox.clone(toolbox.select(population, 1)[0])
if opRandom - cxpb < mutpb:
# Mutation
aspirant = toolbox.mutate(aspirant)[0]
del aspirant.fitness.values
if acceptfunc(len(aspirant)):
producedpop.append(aspirant)
if producesizes:
producedpopsizes.append(len(aspirant))
if producesizes:
return producedpop, producedpopsizes
else:
return producedpop
halflifefunc = lambda x: (x * float(alpha) + beta)
if nbrindsmodel == -1:
nbrindsmodel = max(2000, len(population))
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
record = stats.compile(population) if stats else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
# Begin the generational process
for gen in range(1, ngen + 1):
# Estimation population natural distribution of sizes
naturalpop, naturalpopsizes = _genpop(nbrindsmodel, producesizes=True)
naturalhist = [0] * (max(naturalpopsizes) + 3)
for indsize in naturalpopsizes:
# Kernel density estimation application
naturalhist[indsize] += 0.4
naturalhist[indsize - 1] += 0.2
naturalhist[indsize + 1] += 0.2
naturalhist[indsize + 2] += 0.1
if indsize - 2 >= 0:
naturalhist[indsize - 2] += 0.1
# Normalization
naturalhist = [
val * len(population) / nbrindsmodel for val in naturalhist
]
# Cutoff point selection
sortednatural = sorted(naturalpop, key=lambda ind: ind.fitness)
cutoffcandidates = sortednatural[int(len(population) * rho - 1):]
# Select the cutoff point, with an absolute minimum applied
# to avoid weird cases in the first generations
cutoffsize = max(mincutoff, len(min(cutoffcandidates, key=len)))
# Compute the target distribution
targetfunc = lambda x: (gamma * len(population) * math.log(
2) / halflifefunc(x)) * math.exp(-math.log(2) * (x - cutoffsize) /
halflifefunc(x))
targethist = [
naturalhist[binidx] if binidx <= cutoffsize else targetfunc(binidx)
for binidx in range(len(naturalhist))
]
# Compute the probabilities distribution
probhist = [
t / n if n > 0 else t for n, t in zip(naturalhist, targethist)
]
probfunc = lambda s: probhist[s] if s < len(probhist) else targetfunc(s
)
acceptfunc = lambda s: random.random() <= probfunc(s)
# Generate offspring using the acceptance probabilities
# previously computed
offspring = _genpop(len(population),
pickfrom=naturalpop,
acceptfunc=acceptfunc,
producesizes=False)
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
# Update the hall of fame with the generated individuals
if halloffame is not None:
halloffame.update(offspring)
# Replace the current population by the offspring
population[:] = offspring
# Append the current generation statistics to the logbook
record = stats.compile(population) if stats else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook
def setUp(self):
self.logbook = tools.Logbook()
print
def eaMuCommaLambda(population,
toolbox,
mu,
lambda_,
cxpb,
mutpb,
ngen,
stats=None,
halloffame=None,
verbose=__debug__):
"""This is the :math:`(\mu~,~\lambda)` evolutionary algorithm.
:param population: A list of individuals.
:param toolbox: A :class:`~deap.base.Toolbox` that contains the evolution
operators.
:param mu: The number of individuals to select for the next generation.
:param lambda\_: The number of children to produce at each generation.
:param cxpb: The probability that an offspring is produced by crossover.
:param mutpb: The probability that an offspring is produced by mutation.
:param ngen: The number of generation.
:param stats: A :class:`~deap.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~deap.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population.
First, the individuals having an invalid fitness are evaluated. Then, the
evolutionary loop begins by producing *lambda_* offspring from the
population, the offspring are generated by a crossover, a mutation or a
reproduction proportionally to the probabilities *cxpb*, *mutpb* and 1 -
(cxpb + mutpb). The offspring are then evaluated and the next generation
population is selected **only** from the offspring. Briefly, the operators
are applied as following ::
evaluate(population)
for i in range(ngen):
offspring = varOr(population, toolbox, lambda_, cxpb, mutpb)
evaluate(offspring)
population = select(offspring, mu)
This function expects :meth:`toolbox.mate`, :meth:`toolbox.mutate`,
:meth:`toolbox.select` and :meth:`toolbox.evaluate` aliases to be
registered in the toolbox. This algorithm uses the :func:`varOr`
variation.
"""
assert lambda_ >= mu, "lambda must be greater or equal to mu."
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
# Begin the generational process
for gen in range(1, ngen + 1):
# Vary the population
offspring = varOr(population, toolbox, lambda_, cxpb, mutpb)
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
# Update the hall of fame with the generated individuals
if halloffame is not None:
halloffame.update(offspring)
# Select the next generation population
population[:] = toolbox.select(offspring, mu)
# Update the statistics with the new population
record = stats.compile(population) if stats is not None else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook
def eaSimple(population,
toolbox,
cxpb,
mutpb,
ngen,
stats=None,
halloffame=None,
verbose=__debug__):
"""This algorithm reproduce the simplest evolutionary algorithm as
presented in chapter 7 of [Back2000]_.
:param population: A list of individuals.
:param toolbox: A :class:`~DEAP.base.Toolbox` that contains the evolution
operators.
:param cxpb: The probability of mating two individuals.
:param mutpb: The probability of mutating an individual.
:param ngen: The number of generation.
:param stats: A :class:`~DEAP.tools.Statistics` object that is updated
inplace, optional.
:param halloffame: A :class:`~DEAP.tools.HallOfFame` object that will
contain the best individuals, optional.
:param verbose: Whether or not to log the statistics.
:returns: The final population.
It uses :math:`\lambda = \kappa = \mu` and goes as follow.
It first initializes the population (:math:`P(0)`) by evaluating
every individual presenting an invalid fitness. Then, it enters the
evolution loop that begins by the selection of the :math:`P(g+1)`
population. Then the crossover operator is applied on a proportion of
:math:`P(g+1)` according to the *cxpb* probability, the resulting and the
untouched individuals are placed in :math:`P'(g+1)`. Thereafter, a
proportion of :math:`P'(g+1)`, determined by *mutpb*, is
mutated and placed in :math:`P''(g+1)`, the untouched individuals are
transferred :math:`P''(g+1)`. Finally, those new individuals are evaluated
and the evolution loop continues until *ngen* generations are completed.
Briefly, the operators are applied in the following order ::
evaluate(population)
for i in range(ngen):
offspring = select(population)
offspring = mate(offspring)
offspring = mutate(offspring)
evaluate(offspring)
population = offspring
This function expects :meth:`toolbox.mate`, :meth:`toolbox.mutate`,
:meth:`toolbox.select` and :meth:`toolbox.evaluate` aliases to be
registered in the toolbox.
.. [Back2000] Back, Fogel and Michalewicz, "Evolutionary Computation 1 :
Basic Algorithms and Operators", 2000.
"""
logbook = tools.Logbook()
logbook.header = ['gen', 'nevals'] + (stats.fields if stats else [])
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in population if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
if halloffame is not None:
halloffame.update(population)
record = stats.compile(population) if stats else {}
logbook.record(gen=0, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
# Begin the generational process
for gen in range(1, ngen + 1):
# Select the next generation individuals
offspring = toolbox.select(population, len(population))
# Vary the pool of individuals
offspring = varAnd(offspring, toolbox, cxpb, mutpb)
# Evaluate the individuals with an invalid fitness
invalid_ind = [ind for ind in offspring if not ind.fitness.valid]
fitnesses = toolbox.map(toolbox.evaluate, invalid_ind)
for ind, fit in zip(invalid_ind, fitnesses):
ind.fitness.values = fit
# Update the hall of fame with the generated individuals
if halloffame is not None:
halloffame.update(offspring)
# Replace the current population by the offspring
population[:] = offspring
# Append the current generation statistics to the logbook
record = stats.compile(population) if stats else {}
logbook.record(gen=gen, nevals=len(invalid_ind), **record)
if verbose:
print logbook.stream
return population, logbook