matie

y.pu

#!/usr/bin/python

import random
import string

from functools import partial
from pprint import pprint

TARGET      = "Michael Kilby"
DNA_SIZE    = len(TARGET)
POP_SIZE    = 1000
GENERATIONS = 100
MUTATE_CHANCE = [1,10]  # chance kid will mutate 
RANDO_MATCH = 20 # randomness added to mate selection process

LETTERS_AND_SPACE = string.ascii_letters + ' '

def random_char():
  # Return a random character 
  return random.choice(LETTERS_AND_SPACE)

def make_population():
    # Returns a list of POP_SIZE strings.
    population = [''.join(random_char() for _ in range(DNA_SIZE))
                        for _ in range(POP_SIZE)]
    return population

def trigger_mutation():
    picked = random.randrange(0,MUTATE_CHANCE[1])
    return MUTATE_CHANCE[0] > picked

def mutate(dna):
    # Use MUTATE_CHANCE to create randomness in population
    dna = ''.join(random_char() if trigger_mutation() else g for g in dna)
    return dna

def fitness(dna):
    # Calculate the difference between a character in the same position in the
    # TARGET string.
    # fitness = 0
    correct_chars = sum(1 for a,b in zip(dna, TARGET) if a == b)

    correct_percent = (correct_chars/DNA_SIZE) * 100

    return correct_percent


def mate(mother, father):
    # another comprehension for spped
    kid = ''.join(random.choice([a,b]) for a,b in zip(mother, father))
    mutate(kid)

    return kid

def fitness_random(chaos, dna):
    ''' introduce a bit of randomness to the fitness assessment '''
    r = chaos * random.random() 
    return fitness(dna) + r

def cross(pop):
    ''' take a population adn cross them based on fitness with a bit of rando
    mixed in 
    '''
    #pprint(pop)
    f = fitness  # no random
    f = partial(fitness_random, RANDO_MATCH) # bit'o'random

    weighted_pop = [(p, f(p)) for p in pop]
    weighted_pop = sorted(weighted_pop, key = lambda x:-x[1])
    #pprint(weighted_pop)
    #pprint(weighted_pop)
    its = [iter(weighted_pop)]*2

    for a,b in zip(*its):
        yield a[0], b[0]

def main():
    # Make an initial population
    population = make_population()

    for generation in range(GENERATIONS):
        kids = []
        for a,b in cross(population):
            kids.append(mate(a,b))
            kids.append(mate(a,b))

        population = kids

        if generation % 30 == 0 or False:
            print("Generation {} (pop = {})... Random sample: {} = {}".format(
            generation, 
            len(population),
            population[0],
            fitness(population[0]),
            ))

    best = max(population, key = fitness)
    print('best: {} fitness = {}'.format(
        best,
        fitness(best)
        ))
                

def test():
    #print('testing')
    #print(list(cross(['michyyl', 'Michael', 'ppsdf'])))

    #print(mate('abcdef','123456'))
    print([trigger_mutation() for _ in range(10)])

if __name__ == "__main__": 
    #test()
    main()