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racing_pyai/genetics.py
2019-10-29 11:00:57 +01:00

77 lines
2.4 KiB
Python

import numpy as np
import random
from brain import Neural_Network
from params import MUTATION_RATE, SELECTION_ALG, KWAY_TOURNAMENT_PLAYERS
def kway_selection(brains, exclude=None):
tourn_pool = []
best_play = None
if exclude:
brains = [x for x in brains if x != exclude]
for x in range(KWAY_TOURNAMENT_PLAYERS):
new_play = random.choice(brains)
while new_play in tourn_pool:
new_play = random.choice(brains)
if not best_play or best_play.fitness < new_play.fitness:
best_play = new_play
return best_play
def genetic_selection(brains):
parents_pool = []
half_pop = int(len(brains) / 2)
if SELECTION_ALG == "kway":
for x in range(half_pop):
p1 = kway_selection(brains)
p2 = kway_selection(brains, exclude=p1)
parents_pool.append([p1, p2])
elif SELECTION_ALG == "roulette":
# does not seem very optimized... TBR
# constitute a list where every brain is represented
# proportionnally to its relative fitness
wheel = []
for b in brains:
wheel += [b] * int(b.fitness)
tot_fitness = len(wheel)
# selection of pool/2 pair of parents to reproduce
for _ in range(half_pop):
idx1 = round(random.random() * tot_fitness - 1)
idx2 = round(random.random() * tot_fitness - 1)
parents_pool.append([wheel[idx1], wheel[idx2]])
return parents_pool
def cross_mutate_genes(p1_gene, p2_gene):
child = []
p1_gene = list(p1_gene)
p2_gene = list(p1_gene)
for idx, x in enumerate(p2_gene):
if random.random() > 0.5:
choice = p1_gene[idx]
else:
choice = p2_gene[idx]
# Mutation
if random.random() < MUTATION_RATE:
choice[random.randint(0, len(choice) - 1)] = random.random()
print("Mutation !")
child.append(choice)
return np.array(child)
def genetic_reproduction(parents_pool):
# every pair of parents will produce a mixed child
new_pop = []
for [p1, p2] in parents_pool:
W1_kid = cross_mutate_genes(p1.W1, p2.W1)
W2_kid = cross_mutate_genes(p1.W2, p2.W2)
c_brain1 = Neural_Network(W1=W1_kid, W2=W2_kid)
c_brain2 = Neural_Network(W1=W1_kid, W2=W2_kid)
new_pop.append(c_brain1)
new_pop.append(c_brain2)
return new_pop