IndexError：游戏中的列表索引超出范围

Question

为什么我在pygame游戏中收到IndexError: list index out of range错误消息？

我正在做一个简单的清酒游戏，但是每次蛇吃一个苹果时我增加蛇的长度时，都会出错。

这是碰撞函数

def collision(x1, y1, x2, y2, bsize):
    if x2 + bsize >= x1 >= x2:
        if y2 + bsize >= y1 >= y2:
            return True
    return False

这是吃掉的苹果，如果与自身功能发生冲突就会死掉。

    def eat(self):  # if it eats the apple
        for i in range(self.length):
            if collision(apple.x, apple.y, snake.x[i], snake.y[i], apple.width):  # entering the variables/coordinates
                self.length += 1
                apple.x_multiplier = random.randrange(row)  
                apple.y_multiplier = random.randrange(row)

                apple.x = (r_distance * apple.x_multiplier) + 1  # spawning the apple
                apple.y = (r_distance * apple.y_multiplier) + 1  # at a new coordinate

    def collide(self): # if colide with itself
        for i in range(2, self.length): 
            if collision(snake.x[0], snake.y[0], snake.x[i], snake.y[i], self.width):  # enetring the variables/coordinates
                self.alive = False  # killing the snake