Generate update function with individual logging

generate_update.py

from operator import attrgetter

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)
    
    # Clone to ensure it won't be modified by any side effect
    best_ind = toolbox.clone(max(individuals, key=attrgetter("fitness")))
    
    record = stats.compile(population) if stats is not None else {}
    logbook.record(gen=gen, nevals=len(population), best=best_ind, **record)
    
    if verbose:
        print logbook.stream

return population, logbook