I am trying to implement NEAT for the snake game. My game logic is ready, which is working properly and NEAT configured. But even after 100 generations with population size of 200 per generation, the snakes perform very poorly. I am using neat-python for this.

The game board is 300×300 with grid size of 15. Hence, food and each part of the snake is of size 15×15. Hence, STEP = 15 for snake movement. The neural network has 24 inputs and 4 outputs and no hidden layer as part of the initial NEAT configuration. Activation function used is sigmoid.

Below are the inputs:

snakeHeadX, snakeHeadY, snakeHeadBottomDist, snakeHeadRightDist, snakeTailX, snakeTailY, snakeLength, moveCount, moveToFood, food.x, food.y, foodBottomDist, foodRightDist, snakeFoodDistEuclidean, snakeFoodDistManhattan, viewDirections[0], viewDirections[1], viewDirections[2], viewDirections[3], viewDirections[4], viewDirections[5], viewDirections[6], viewDirections[7], deltaFoodDist

Here, viewDirections[0] – [7] denote what the snake finds looking in 8 different directions. In each direction, the snake will check for food and it’s own body. If it finds neither food nor body, value for that direction will be 0, if it finds only food, it will be 1, if finds only body, it will be 2 and if both body and food is found, then value will be 3. I have attached the implementation to find viewDirections list below as well.

The outputs are:

output[0] –> for moving up, output[1] –> for moving down, output[2] –> for moving left, output[3] –> for moving right

The problem is the snake barely ever eats more than 2 food. The snake is unable to learn where the food is, reduce distance to food and ultimately eat it, but avoiding wall and the body at the same time. Need help if anyone here can guide me with what I am doing wrong, or what I am missing that I need to incorporate in this to make it work.

Below is the eval_genome function:

ef main(genomes, config): clock = pygame.time.Clock() win = pygame.display.set_mode((WIN_WIDTH, WIN_HEIGHT)) for genome_id, g in genomes: net = neat.nn.FeedForwardNetwork.create(g, config) g.fitness = 0 snake = Snake() food = Food(snake.body) run = True UP = DOWN = RIGHT = LEFT = MOVE_SNAKE = False moveToFood = 0 score = 0 moveCount = 0 while run: clock.tick(90) for event in pygame.event.get(): if event.type == pygame.QUIT: run = False snakeHeadX = snake.body[0]['x'] snakeHeadY = snake.body[0]['y'] snakeTailX = snake.body[len(snake.body)-1]['x'] snakeTailY = snake.body[len(snake.body)-1]['y'] snakeLength = len(snake.body) snakeHeadBottomDist = WIN_HEIGHT - snakeHeadY - STEP snakeHeadRightDist = WIN_WIDTH - snakeHeadX - STEP foodBottomDist = WIN_HEIGHT - food.y - STEP foodRightDist = WIN_WIDTH - food.x - STEP snakeFoodDistEuclidean = math.sqrt((snakeHeadX - food.x)**2 + (snakeHeadY - food.y)**2) snakeFoodDistManhattan = abs(snakeHeadX - food.x) + abs(snakeHeadY - food.y) viewDirections = snake.checkDirections(food, UP, DOWN, LEFT, RIGHT) if not MOVE_SNAKE: deltaFoodDist = 0 outputs = net.activate((snakeHeadX, snakeHeadY, snakeHeadBottomDist, snakeHeadRightDist, snakeTailX, snakeTailY, snakeLength, moveCount, moveToFood, food.x, food.y, foodBottomDist, foodRightDist, snakeFoodDistEuclidean, snakeFoodDistManhattan, viewDirections[0], viewDirections[1], viewDirections[2], viewDirections[3], viewDirections[4], viewDirections[5], viewDirections[6], viewDirections[7], deltaFoodDist)) if (outputs[0] == max(outputs) and not DOWN): snake.setDir(0,-1) UP = True LEFT = False RIGHT = False MOVE_SNAKE = True elif (outputs[1] == max(outputs) and not UP): snake.setDir(0,1) DOWN = True LEFT = False RIGHT = False MOVE_SNAKE = True elif (outputs[2] == max(outputs) and not RIGHT): snake.setDir(-1,0) LEFT = True UP = False DOWN = False MOVE_SNAKE = True elif (outputs[3] == max(outputs) and not LEFT): snake.setDir(1,0) RIGHT = True UP = False DOWN = False MOVE_SNAKE = True elif (not MOVE_SNAKE): if (outputs[0] == max(outputs)): snake.setDir(0,-1) UP = True MOVE_SNAKE = True elif (outputs[1] == max(outputs)): snake.setDir(0,1) DOWN = True MOVE_SNAKE = True elif (outputs[2] == max(outputs)): snake.setDir(-1,0) LEFT = True MOVE_SNAKE = True elif (outputs[3] == max(outputs)): snake.setDir(1,0) RIGHT = True MOVE_SNAKE = True win.fill((0, 0, 0)) food.showFood(win) if(MOVE_SNAKE): snake.update() newSnakeHeadX = snake.body[0]['x'] newSnakeHeadY = snake.body[0]['y'] newFoodDist = math.sqrt((newSnakeHeadX - food.x)**2 + (newSnakeHeadY - food.y)**2) deltaFoodDist = newFoodDist - snakeFoodDistEuclidean moveCount += 1 g.fitness += 0.01 if (deltaFoodDist < 0): g.fitness += 5 else: g.fitness -= 50 if(snake.collision()): if score != 0: print('FINAL SCORE IS: '+ str(score)) g.fitness -= 300 break snake.show(win) if(snake.eat(food,win)): g.fitness += 15 score += 1 if score == 1 : moveToFood = moveCount else: moveToFood = moveCount - moveToFood food.foodLocation(snake.body) food.showFood(win) 

Below is the checkDirections function implemented in Snake class which gives the viewDirections list as output:

def checkDirections(self, food, up, down, left, right): ''' x+STEP, y-STEP x+STEP, y+STEP x-STEP, y-STEP x-STEP, y+STEP x+STEP, y x, y-STEP x, y+STEP x-STEP, y ''' view = [] x = self.xdir y = self.ydir view.append(self.check(x, y, STEP, -STEP, food.x, food.y)) view.append(self.check(x, y, STEP, STEP, food.x, food.y)) view.append(self.check(x, y, -STEP, -STEP, food.x, food.y)) view.append(self.check(x, y, -STEP, STEP, food.x, food.y)) view.append(self.check(x, y, STEP, 0, food.x, food.y)) view.append(self.check(x, y, 0, -STEP, food.x, food.y)) view.append(self.check(x, y, 0, STEP, food.x, food.y)) view.append(self.check(x, y, -STEP, 0, food.x, food.y)) if up == True: view[6] = -999 elif down == True: view[5] = -999 elif left == True: view[4] == -999 elif right == True: view[7] == -999 return view def check(self, x, y, xIncrement, yIncrement, foodX, foodY): value = 0 foodFound = False bodyFound = False while (x >= 0 and x < WIN_WIDTH and y >= 0 and y < WIN_HEIGHT): x += xIncrement y += yIncrement if (not foodFound): if (foodX == x and foodY == y): foodFound = True if (not bodyFound): for i in range(1, len(self.body)): if ((x == self.body[i]['x']) and (y == self.body[i]['y'])): bodyFound = True if (not bodyFound and not foodFound): value = 0 elif (not bodyFound and foodFound): value = 1 elif (bodyFound and not foodFound): value = 2 else: value = 3 return value