问题描述
我正在尝试训练AI使用遗传算法玩蛇。我正在使用Python库NEAT进行培训。问题在于培训无法融合，AI无法学习。这是训练代码：
class SnakeEnv():
def __init__(self,screen):
self.action_space = np.array([0,1,2,3])
self.state = None
pygame.init()
self.screen = screen
self.snakes = []
self.total_reward = 0
def reset(self):
self.__init__()
def get_state(self):
return np.reshape(self.snake.board,(400,1)).T / 5
def render(self,snake):
self.screen.fill((0,0))
snake.food.render()
snake.render()
pygame.display.flip()
def step(self,snake,action):
snake.move(action)
self.render(snake)
def close(self):
pygame.quit()
def eval_genomes(self,genomes,config):
global nets_g
nets_g = []
nets = []
snakes = []
global ge_g
ge_g = []
ge = []
for genome_id,genome in genomes:
genome.fitness = 0
net = neat.nn.FeedForwardNetwork.create(genome,config)
nets.append(net)
snakes.append(Snake(self.screen))
ge.append(genome)
ge_g = ge.copy()
nets_g = nets.copy()
run = True
#Main loop
while run:
for event in pygame.event.get():
if event.type == pygame.QUIT:
run = False
pygame.quit()
quit()
break
for x,snake in enumerate(snakes):
if(snake.done):
continue
ge[x].fitness += 0.1
"""
Inputs to the neural net:
Vertical distance from food to head
Horizontal distance from food to head
Vertical distance to nearest wall from head
Horizontal distance to nearest wall from head
distance from head to body segment (default -1)
"""
snake_x = snake.head.x
snake_y = snake.head.y
food_x = snake.food.x
food_y = snake.food.y
food_vert = snake_y - food_y
food_horz = snake_x - food_x
wall_vert = min(snake_y,600 - snake_y)
wall_horz = min(snake_x,600 - snake_x)
body_front = snake.body_front()
output = np.argmax(nets[snakes.index(snake)].activate((food_vert,food_horz,wall_vert,wall_horz,body_front)))
state = snake.move(output)
if state["Food"] == True:
ge[snakes.index(snake)].fitness += 1
if state["Died"] == True:
ge[snakes.index(snake)].fitness -= 1
#nets.pop(snakes.index(snake))
#ge.pop(snakes.index(snake))
#snakes.pop(snakes.index(snake))
all_done = [snake.done for snake in snakes]
if(False not in all_done):
run = False
def run(self,config_file):
config = neat.config.Config(neat.DefaultGenome,neat.DefaultReproduction,neat.DefaultSpeciesSet,neat.DefaultStagnation,config_file)
population = neat.Population(config)
population.add_reporter(neat.StdOutReporter(True))
stats = neat.StatisticsReporter()
population.add_reporter(stats)
best = population.run(self.eval_genomes,200)
print('\nBest genome:\n{!s}'.format(best))
best_net = nets_g[ge_g.index(best)]
pickle.dump(best_net,open('best.pkl','wb'))
（假装我的代码缩进了，编辑器由于某种原因无法正常工作）
这是conf.txt文件：
[NEAT]
fitness_criterion = max
fitness_threshold = 20
pop_size = 50
reset_on_extinction = False
[DefaultGenome]
# node activation options
activation_default = relu
activation_mutate_rate = 0.0
activation_options = relu
# node aggregation options
aggregation_default = sum
aggregation_mutate_rate = 0.0
aggregation_options = sum
# node bias options
bias_init_mean = 0.0
bias_init_stdev = 1.0
bias_max_value = 10.0
bias_min_value = -10.0
bias_mutate_power = 0.5
bias_mutate_rate = 0.9
bias_replace_rate = 0.1
# genome compatibility options
compatibility_disjoint_coefficient = 1.0
compatibility_weight_coefficient = 0.5
# connection add/remove rates
conn_add_prob = 0.7
conn_delete_prob = 0.7
# connection enable options
enabled_default = True
enabled_mutate_rate = 0.01
Feed_forward = True
initial_connection = full
# node add/remove rates
node_add_prob = 0.7
node_delete_prob = 0.7
# network parameters
num_hidden = 0
num_inputs = 5
num_outputs = 4
# node response options
response_init_mean = 1.0
response_init_stdev = 0.0
response_max_value = 30.0
response_min_value = -30.0
response_mutate_power = 0.0
response_mutate_rate = 0.0
response_replace_rate = 0.0
# connection weight options
weight_init_mean = 0.0
weight_init_stdev = 1.0
weight_max_value = 30
weight_min_value = -30
weight_mutate_power = 0.5
weight_mutate_rate = 0.8
weight_replace_rate = 0.1
[DefaultSpeciesSet]
compatibility_threshold = 3.0
[DefaultStagnation]
species_fitness_func = max
max_stagnation = 20
species_elitism = 2
[DefaultReproduction]
elitism = 2
survival_threshold = 0.2
您可以看到我训练了200代。结果很奇怪。这条蛇一直只吃一点食物，但立即撞到了墙。这是一种学习，但还不够全面。我试图让它训练更多代，但是没有区别。我认为问题可能出在我对神经网络的输入上，但我不确定。
编辑：我更改了网络体系结构，以使其现在具有4个带有relu激活的输出节点。现在的问题是代码冻结在计算输出的步骤（output = np.argmax(nets[snakes.index(snake)].activate((food_vert,body_front)))）
解决方法
浏览代码后，您似乎遇到了一些错误：
for x,snake in enumerate(snakes):
ge[x].fitness += 0.1
在for循环中，您正在pop()列出snakes和ge列表中的元素。在Python中，永远不要在迭代列表时更改列表。在循环的后面，您将使用由snakes.index(snake)插入的x来索引同一列表。因此，维持生命的奖励可能归功于错误的蛇。
您可以在迭代之前复制列表，但是到处重复snakes.index(snake)也是一种反模式。您需要找到其他解决方案。例如，您可以使用snake.dead标志。
输出形状
您似乎正在将单个神经元的输出缩放到整数范围。对于神经网络，这使任务有些困难（但并非没有可能），因为近距离的数字实际上并没有映射到类似的动作。
更常见的方法是为每个输出使用单独的神经元，并选择激活程度最高的动作。 （或者使用softmax选择具有随机概率的动作。这会增加噪音，但会使健身环境更加平滑，因为即使权重的很小变化也会对健身产生一定影响。）
一般建议
您不能期望编写无错误的代码。当您的代码属于优化循环的一部分时，调试会非常麻烦，因为优化会更改错误的影响。
首先以更简单的设置运行代码。例如，您可以忽略神经网络的输出，而始终执行相同的操作（或随机操作）。想想应该发生什么。也许手动逐步跟踪一些蛇及其奖励，例如带有打印语句。
重点是：减少同时调试的事物数量。