mattia wrote:
> The last question: how can I improve readability in this piece of code?
>
> def crossover(pop, prob=0.6):
> """
> With a crossover probability cross over the parents to form new
> offspring. If no crossover was performed, offspring is the exact copy
> of parents. """
> cpop = []
> for i in range(0, len(pop), 2):
> # crossover
> if prob > random():
> crossover_point = randint(0, len(pop[i])-1)
> nchromosome1 = pop[i][:crossover_point] +
> pop[i+1][crossover_point:] nchromosome2 =
> pop[i+1][:crossover_point] + pop[i][crossover_point:]
> else:
> nchromosome1 = pop[i][:]
> nchromosome2 = pop[i+1][:]
> cpop += [nchromosome1] + [nchromosome2]
I'd write that as
cpop.append(nchromosome1)
cpop.append(nchromosome2)
thus avoiding the intermediate lists.
> return cpop
>
> And with this one my example is complete!
Just for fun here's an alternative version of your function
def generate_crossover(pop, prob):
for a, b in zip(*[iter(pop)]*2):
if prob > random():
cut = randrange(len(a))
a, b = a[:cut] + b[cut:], b[:cut] + a[cut:]
yield a
yield b
def crossover(pop, prob=0.6):
return list(generate_crossover(pop, prob))
but as the original is a bit clearer I recommend that you stick with it.
Peter
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