帮我生成一个贪吃蛇游戏的python代码

好的，以下是一个简单的贪吃蛇游戏的Python代码：

import pygame
import random

# 初始化pygame模块
pygame.init()

# 设置游戏界面大小
screen_width = 480
screen_height = 480
screen = pygame.display.set_mode((screen_width, screen_height))

# 设置游戏标题
pygame.display.set_caption("贪吃蛇游戏")

# 设置颜色
white = (255, 255, 255)
black = (0, 0, 0)
red = (255, 0, 0)
green = (0, 255, 0)

# 设置字体
font = pygame.font.SysFont(None, 25)

# 设置蛇的大小和速度
snake_size = 10
snake_speed = 15

# 定义函数，显示文字
def display_text(msg, color):
    text = font.render(msg, True, color)
    screen.blit(text, [screen_width/6, screen_height/3])

# 定义函数，绘制蛇
def draw_snake(snake_size, snake_pixels):
    for pixel in snake_pixels:
        pygame.draw.rect(screen, green, [pixel[0], pixel[1], snake_size, snake_size])

# 定义函数，运行游戏
def run_game():
    # 初始化蛇的位置和长度
    snake_x = screen_width / 2
    snake_y = screen_height / 2
    snake_pixels = [[snake_x, snake_y]]
    snake_length = 1

    # 初始化食物的位置
    food_x = round(random.randrange(0, screen_width - snake_size) / 10.0) * 10.0
    food_y = round(random.randrange(0, screen_height - snake_size) / 10.0) * 10.0

    # 设置初始方向
    direction = "up"
    change_to = direction

    # 设置游戏结束标志
    game_over = False

    # 开始游戏循环
    while not game_over:
        # 监听事件
        for event in pygame.event.get():
            # 如果是退出事件，则退出游戏
            if event.type == pygame.QUIT:
                game_over = True

            # 如果是键盘事件，则改变方向
            if event.type == pygame.KEYDOWN:
                if event.key == pygame.K_UP:
                    change_to = "up"
                if event.key == pygame.K_DOWN:
                    change_to = "down"
                if event.key == pygame.K_LEFT:
                    change_to = "left"
                if event.key == pygame.K_RIGHT:
                    change_to = "right"

        # 根据方向改变蛇的位置
        if change_to == "up" and direction != "down":
            direction = "up"
        if change_to == "down" and direction != "up":
            direction = "down"
        if change_to == "left" and direction != "right":
            direction = "left"
        if change_to == "right" and direction != "left":
            direction = "right"

        # 根据方向计算蛇头的位置
        if direction == "up":
            snake_y -= snake_size
        if direction == "down":
            snake_y += snake_size
        if direction == "left":
            snake_x -= snake_size
        if direction == "right":
            snake_x += snake_size

        # 判断是否吃到食物
        if snake_x == food_x and snake_y == food_y:
            food_x = round(random.randrange(0, screen_width - snake_size) / 10.0) * 10.0
            food_y = round(random.randrange(0, screen_height - snake_size) / 10.0) * 10.0
            snake_length += 1

        # 更新蛇的位置
        snake_pixels.append([snake_x, snake_y])
        if len(snake_pixels) > snake_length:
            del snake_pixels[0]

        # 判断是否碰到墙壁或自己的身体
        if snake_x < 0 or snake_x > screen_width - snake_size or snake_y < 0 or snake_y > screen_height - snake_size:
            game_over = True
        for pixel in snake_pixels[:-1]:
            if pixel == [snake_x, snake_y]:
                game_over = True

        # 设置背景颜色
        screen.fill(black)

        # 绘制食物和蛇
        pygame.draw.rect(screen, red, [food_x, food_y, snake_size, snake_size])
        draw_snake(snake_size, snake_pixels)

        # 更新屏幕
        pygame.display.update()

        # 判断游戏是否结束
        if game_over:
            display_text("游戏结束，按Q退出或者按R重新开始", white)
            pygame.display.update()

            # 等待用户选择
            while True:
                for event in pygame.event.get():
                    if event.type == pygame.KEYDOWN:
                        if event.key == pygame.K_q:
                            pygame.quit()
                            quit()
                        if event.key == pygame.K_r:
                            run_game()

        # 设置游戏速度
        clock = pygame.time.Clock()
        clock.tick(snake_speed)

# 运行游戏
run_game()

请注意，此代码是一个简单的示例，您可以根据需要进行修改和优化。