200行Python代码实现2048

一、实验说明

1. 环境登录

无需密码自动登录，系统用户名shiyanlou

2. 环境介绍

本实验环境采用带桌面的Ubuntu Linux环境，实验中会用到桌面上的程序：

LX终端（LXTerminal）: Linux命令行终端，打开后会进入Bash环境，可以使用Linux命令
GVim：非常好用的编辑器，最简单的用法可以参考课程Vim编辑器

3. 环境使用

使用GVim编辑器输入实验所需的代码及文件，使用LX终端（LXTerminal）运行所需命令进行操作。

实验报告可以在个人主页中查看，其中含有每次实验的截图及笔记，以及每次实验的有效学习时间（指的是在实验桌面内操作的时间，如果没有操作，系统会记录为发呆时间）。这些都是您学习的真实性证明。

4. 知识点

本节实验中将学习和实践以下知识点：

Python基本知识
状态机的概念

二、实验内容

是的，又是2048，这回我们是用 Python 实现，只需要200行代码，不用很麻烦很累就可以写一个 2048 游戏出来。

实验楼上已有的 2048 课程：

游戏玩法这里就不再赘述了，还会有比亲自玩一遍体会规则更快的的吗：）

2048 原版游戏地址：http://gabrielecirulli.github.io/2048

创建游戏文件 2048.py

首先导入需要的包：

import curses

from random import randrange, choice

from collections import defaultdict

主逻辑

用户行为

所有的有效输入都可以转换为"上，下，左，右，游戏重置，退出"这六种行为，用 actions 表示

actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']

有效输入键是最常见的 W（上），A（左），S（下），D（右），R（重置），Q（退出），这里要考虑到大写键开启的情况，获得有效键值列表：

letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']

将输入与行为进行关联：

actions_dict = dict(zip(letter_codes, actions * 2))

状态机

处理游戏主逻辑的时候我们会用到一种十分常用的技术：状态机，或者更准确的说是有限状态机（FSM）

你会发现 2048 游戏很容易就能分解成几种状态的转换。

state 存储当前状态， state_actions 这个词典变量作为状态转换的规则，它的 key 是状态，value 是返回下一个状态的函数：

Init: init()
- Game
Game: game()
- Game
- Win
- GameOver
- Exit
Win: lambda: not_game('Win')
- Init
- Exit
Gameover: lambda: not_game('Gameover')
- Init
- Exit
Exit: 退出循环

状态机会不断循环，直到达到 Exit 终结状态结束程序。

下面是经过提取的主逻辑的代码，会在后面进行补全：

def main(stdscr):

    def init():

        #重置游戏棋盘

        return 'Game'

    def not_game(state):

        #画出 GameOver 或者 Win 的界面

        #读取用户输入得到action，判断是重启游戏还是结束游戏

        responses = defaultdict(lambda: state) ＃默认是当前状态，没有行为就会一直在当前界面循环

        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #对应不同的行为转换到不同的状态

        return responses[action]

    def game():

        #画出当前棋盘状态

        #读取用户输入得到action

        if action == 'Restart':

            return 'Init'

        if action == 'Exit':

            return 'Exit'

        #if 成功移动了一步:

            if 游戏胜利了:

                return 'Win'

            if 游戏失败了:

                return 'Gameover'

        return 'Game'

    state_actions = {

            'Init': init,

            'Win': lambda: not_game('Win'),

            'Gameover': lambda: not_game('Gameover'),

            'Game': game

        }

    state = 'Init'

    #状态机开始循环

    while state != 'Exit':

        state = state_actions[state]()

用户输入处理

阻塞＋循环，直到获得用户有效输入才返回对应行为：

def get_user_action(keyboard):

    char = "N"

    while char not in actions_dict:

        char = keyboard.getch()

    return actions_dict[char]

矩阵转置与矩阵逆转

加入这两个操作可以大大节省我们的代码量，减少重复劳动，看到后面就知道了。

矩阵转置：

def transpose(field):

    return [list(row) for row in zip(*field)]

矩阵逆转（不是逆矩阵）：

def invert(field):

    return [row[::-1] for row in field]

创建棋盘

初始化棋盘的参数，可以指定棋盘的高和宽以及游戏胜利条件，默认是最经典的 4x4～2048。

class GameField(object):

def __init__(self, height=4, width=4, win=2048):

    self.height = height       #高

    self.width = width         #宽

    self.win_value = 2048      #过关分数

    self.score = 0             #当前分数

    self.highscore = 0         #最高分

    self.reset()               #棋盘重置

棋盘操作

随机生成一个 2 或者 4

def spawn(self):

        new_element = 4 if randrange(100) > 89 else 2

        (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] == 0])

        self.field[i][j] = new_element

重置棋盘

def reset(self):

    if self.score > self.highscore:

        self.highscore = self.score

    self.score = 0

    self.field = [[0 for i in range(self.width)] for j in range(self.height)]

    self.spawn()

    self.spawn()

一行向左合并

(注：这一操作是在 move 内定义的，拆出来是为了方便阅读)

def move_row_left(row):

    def tighten(row): # 把零散的非零单元挤到一块

        new_row = [i for i in row if i != 0]

        new_row += [0 for i in range(len(row) - len(new_row))]

        return new_row

    def merge(row): # 对邻近元素进行合并

        pair = False

        new_row = []

        for i in range(len(row)):

            if pair:

                new_row.append(2 * row[i])

                self.score += 2 * row[i]

                pair = False

            else:

                if i + 1 < len(row) and row[i] == row[i + 1]:

                    pair = True

                    new_row.append(0)

                else:

                    new_row.append(row[i])

        assert len(new_row) == len(row)

        return new_row

    #先挤到一块再合并再挤到一块

    return tighten(merge(tighten(row)))

棋盘走一步

通过对矩阵进行转置与逆转，可以直接从左移得到其余三个方向的移动操作

def move(self, direction):

    def move_row_left(row):

        #一行向左合并

    moves = {}

    moves['Left']  = lambda field: [move_row_left(row) for row in field]

    moves['Right'] = lambda field: invert(moves['Left'](invert(field)))

    moves['Up']    = lambda field: transpose(moves['Left'](transpose(field)))

    moves['Down']  = lambda field: transpose(moves['Right'](transpose(field)))

    if direction in moves:

        if self.move_is_possible(direction):

            self.field = moves[direction](self.field)

            self.spawn()

            return True

        else:

            return False

判断输赢

def is_win(self):

    return any(any(i >= self.win_value for i in row) for row in self.field)

def is_gameover(self):

    return not any(self.move_is_possible(move) for move in actions)

判断能否移动

def move_is_possible(self, direction):

    def row_is_left_movable(row):

        def change(i):

            if row[i] == 0 and row[i + 1] != 0: # 可以移动

                return True

            if row[i] != 0 and row[i + 1] == row[i]: # 可以合并

                return True

            return False

        return any(change(i) for i in range(len(row) - 1))

    check = {}

    check['Left']  = lambda field: any(row_is_left_movable(row) for row in field)

    check['Right'] = lambda field: check['Left'](invert(field))

    check['Up']    = lambda field: check['Left'](transpose(field))

    check['Down']  = lambda field: check['Right'](transpose(field))

    if direction in check:

        return check[direction](self.field)

    else:

        return False

绘制游戏界面

（注：这一步是在棋盘类内定义的）

def draw(self, screen):

    help_string1 = '(W)Up (S)Down (A)Left (D)Right'

    help_string2 = '     (R)Restart (Q)Exit'

    gameover_string = '           GAME OVER'

    win_string = '          YOU WIN!'

    def cast(string):

        screen.addstr(string + '\n')

    #绘制水平分割线

    def draw_hor_separator():

        line = '+' + ('+------' * self.width + '+')[1:]

        separator = defaultdict(lambda: line)

        if not hasattr(draw_hor_separator, "counter"):

            draw_hor_separator.counter = 0

        cast(separator[draw_hor_separator.counter])

        draw_hor_separator.counter += 1

    def draw_row(row):

        cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

    screen.clear()

    cast('SCORE: ' + str(self.score))

    if 0 != self.highscore:

        cast('HGHSCORE: ' + str(self.highscore))

    for row in self.field:

        draw_hor_separator()

        draw_row(row)

    draw_hor_separator()

    if self.is_win():

        cast(win_string)

    else:

        if self.is_gameover():

            cast(gameover_string)

        else:

            cast(help_string1)

    cast(help_string2)

完成主逻辑

完成以上工作后，我们就可以补完主逻辑了！

def main(stdscr):

    def init():

        #重置游戏棋盘

        game_field.reset()

        return 'Game'

    def not_game(state):

        #画出 GameOver 或者 Win 的界面

        game_field.draw(stdscr)

        #读取用户输入得到action，判断是重启游戏还是结束游戏

        action = get_user_action(stdscr)

        responses = defaultdict(lambda: state) #默认是当前状态，没有行为就会一直在当前界面循环

        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #对应不同的行为转换到不同的状态

        return responses[action]

    def game():

        #画出当前棋盘状态

        game_field.draw(stdscr)

        #读取用户输入得到action

        action = get_user_action(stdscr)

        if action == 'Restart':

            return 'Init'

        if action == 'Exit':

            return 'Exit'

        if game_field.move(action): # move successful

            if game_field.is_win():

                return 'Win'

            if game_field.is_gameover():

                return 'Gameover'

        return 'Game'

    state_actions = {

            'Init': init,

            'Win': lambda: not_game('Win'),

            'Gameover': lambda: not_game('Gameover'),

            'Game': game

        }

    curses.use_default_colors()

    game_field = GameField(win=32)

    state = 'Init'

    #状态机开始循环

    while state != 'Exit':

        state = state_actions[state]()

运行

填上最后一行代码：

curses.wrapper(main)

运行看看吧！

$ python 2048.py

全部代码的注释

#-*- coding:utf-8 -*-

import curses #引入curses模块，curses是一个在Linux/Unix下广泛应用的图形函数库.，作用是可以绘制在DOS下的用户界面和漂亮的图形。

from random import randrange, choice # 从random模块引入randrange,choice这两个类

from collections import defaultdict #从collections引入defaultdict这个类

letter_codes = [ord(ch) for ch in 'WASDRQwasdrq'] #ord函数是把字符转换成对应的数字

actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit'] #上，左，下，右，重启，退出

actions_dict = dict(zip(letter_codes, actions * 2)) #把字母与动作对应起来。 zip是把元组中的值对应起来。

#############################
W Up
A Left
S Down
D Right
R Restart
Q Exit

w Up
a Left
s Down
d Right
r Restart
Q Exit
##############################################

def get_user_action(keyboard):

    char = "N" #char的初始值为N

    while char not in actions_dict:

        char = keyboard.getch()

    return actions_dict[char] #阻塞＋循环，直到获得用户有效输入才返回对应行为

def transpose(field):

    return [list(row) for row in zip(*field)] #zip函数里边加*号，是把行变列，列变行。所以这句代码是行列转置

def invert(field):

    return [row[::-1] for row in field] #这句代码是把列表前后颠倒

class GameField(object): #创建一个叫做GameField的类，用来创建棋盘

    def __init__(self, height=4, width=4, win=2048): 这个类三个参数

        self.height = height  #高

        self.width = width #宽

        self.win_value = win#过关分数

        self.score = 0#当前分数

        self.highscore = 0#最高分

        self.reset()#重置棋盘

    def reset(self):#定义一个reset函数

        if self.score > self.highscore:#如果当前分数大于最高分，那么把当前分数赋值给最高分

            self.highscore = self.score

        self.score = 0#当前分数恢复到0分

        self.field = [[0 for i in range(self.width)] for j in range(self.height)]#横纵坐标恢复到（0,0）

        self.spawn()#调用spawn这个函数

        self.spawn()

    def move(self, direction):#定义move函数

        def move_row_left(row):#向左移

            def tighten(row): # squeese non-zero elements together 把零散的非零单元挤到一块

                new_row = [i for i in row if i != 0] #如果i不等于零，把他们赋值到new_row这个元组中

                new_row += [0 for i in range(len(row) - len(new_row))]#其余位置用0补充

                return new_row#返回这个元组

            def merge(row):#定义merge函数，用来合并单元

                pair = False#pair初始值为假

                new_row = []#new_row初始值为空

                for i in range(len(row)):#让i在格子里循环

                    if pair:如果pair为真

                        new_row.append(2 * row[i])#那么把把row【i】的值乘以2，追加到new_row后边

                        self.score += 2 * row[i]#并且得分为row【i】的值乘以2

                        pair = False#pair重新赋值为假

                    else:如果pair为真

                        if i + 1 < len(row) and row[i] == row[i + 1]:#如果i+1还没到边界，并且此时的row【i】=row【i+1】

                            pair = True #那么pair为真

                            new_row.append(0)#new_row后追加零

                        else:

                            new_row.append(row[i])#否则追加row【i】

                assert len(new_row) == len(row) #提醒两者长度一致

                return new_row

            return tighten(merge(tighten(row))) #反复合并，知道不能合并为止

        moves = {}

        moves['Left']  = lambda field:                              \

                [move_row_left(row) for row in field]#做移动

        moves['Right'] = lambda field:                              \

                invert(moves['Left'](invert(field)))#invert是逆转

        moves['Up']    = lambda field:                              \

                transpose(moves['Left'](transpose(field)))#transpose是转置

        moves['Down']  = lambda field:                              \

                transpose(moves['Right'](transpose(field)))

        if direction in moves:

            if self.move_is_possible(direction):#如果移动方向在四个方向上，

                self.field = moves[direction](self.field)那么调用moves函数

                self.spawn()#产生随机数

                return True

            else:

                return False

    def is_win(self):

        return any(any(i >= self.win_value for i in row) for row in self.field)

    def is_gameover(self):

        return not any(self.move_is_possible(move) for move in actions)

    def draw(self, screen):

        help_string1 = '(W)Up (S)Down (A)Left (D)Right'

        help_string2 = '     (R)Restart (Q)Exit'

        gameover_string = '           GAME OVER'

        win_string = '          YOU WIN!'

        def cast(string):

            screen.addstr(string + '\n')

        def draw_hor_separator():

            line = '+' + ('+------' * self.width + '+')[1:]

            separator = defaultdict(lambda: line)

            if not hasattr(draw_hor_separator, "counter"):

                draw_hor_separator.counter = 0

            cast(separator[draw_hor_separator.counter])

            draw_hor_separator.counter += 1

        def draw_row(row):

            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()

        cast('SCORE: ' + str(self.score))

        if 0 != self.highscore:

            cast('HGHSCORE: ' + str(self.highscore))

        for row in self.field:

            draw_hor_separator()

            draw_row(row)

        draw_hor_separator()

        if self.is_win():

            cast(win_string)

        else:

            if self.is_gameover():

                cast(gameover_string)

            else:

                cast(help_string1)

        cast(help_string2)

    def spawn(self):

        new_element = 4 if randrange(100) > 89 else 2

        (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] == 0])

        self.field[i][j] = new_element

    def move_is_possible(self, direction):

        def row_is_left_movable(row):

            def change(i): # true if there'll be change in i-th tile

                if row[i] == 0 and row[i + 1] != 0: # Move

                    return True

                if row[i] != 0 and row[i + 1] == row[i]: # Merge

                    return True

                return False

            return any(change(i) for i in range(len(row) - 1))

        check = {}

        check['Left']  = lambda field:                              \

                any(row_is_left_movable(row) for row in field)

        check['Right'] = lambda field:                              \

                 check['Left'](invert(field))

        check['Up']    = lambda field:                              \

                check['Left'](transpose(field))

        check['Down']  = lambda field:                              \

                check['Right'](transpose(field))

        if direction in check:

            return check[direction](self.field)

        else:

            return False

def main(stdscr):

    def init():

        #重置游戏棋盘

        game_field.reset()

        return 'Game'

    def not_game(state):

        #画出 GameOver 或者 Win 的界面

        game_field.draw(stdscr)

        #读取用户输入得到action，判断是重启游戏还是结束游戏

        action = get_user_action(stdscr)

        responses = defaultdict(lambda: state) #默认是当前状态，没有行为就会一直在当前界面循环

        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #对应不同的行为转换到不同的状态

        return responses[action]

    def game():

        #画出当前棋盘状态

        game_field.draw(stdscr)

        #读取用户输入得到action

        action = get_user_action(stdscr)

        if action == 'Restart':

            return 'Init'

        if action == 'Exit':

            return 'Exit'

        if game_field.move(action): # move successful

            if game_field.is_win():

                return 'Win'

            if game_field.is_gameover():

                return 'Gameover'

        return 'Game'

    state_actions = {

            'Init': init,

            'Win': lambda: not_game('Win'),

            'Gameover': lambda: not_game('Gameover'),

            'Game': game

        }

    curses.use_default_colors()

    game_field = GameField(win=32)

    state = 'Init'

    #状态机开始循环

    while state != 'Exit':

        state = state_actions[state]()

curses.wrapper(main)

全部代码

#-*- coding:utf-8 -*-

import curses

from random import randrange, choice # generate and place new tile

from collections import defaultdict

letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']

actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']

actions_dict = dict(zip(letter_codes, actions * 2))

def get_user_action(keyboard):

    char = "N"

    while char not in actions_dict:

        char = keyboard.getch()

    return actions_dict[char]

def transpose(field):

    return [list(row) for row in zip(*field)]

def invert(field):

    return [row[::-1] for row in field]

class GameField(object):

    def __init__(self, height=4, width=4, win=2048):

        self.height = height

        self.width = width

        self.win_value = win

        self.score = 0

        self.highscore = 0

        self.reset()

    def reset(self):

        if self.score > self.highscore:

            self.highscore = self.score

        self.score = 0

        self.field = [[0 for i in range(self.width)] for j in range(self.height)]

        self.spawn()

        self.spawn()

    def move(self, direction):

        def move_row_left(row):

            def tighten(row): # squeese non-zero elements together

                new_row = [i for i in row if i != 0]

                new_row += [0 for i in range(len(row) - len(new_row))]

                return new_row

            def merge(row):

                pair = False

                new_row = []

                for i in range(len(row)):

                    if pair:

                        new_row.append(2 * row[i])

                        self.score += 2 * row[i]

                        pair = False

                    else:

                        if i + 1 < len(row) and row[i] == row[i + 1]:

                            pair = True

                            new_row.append(0)

                        else:

                            new_row.append(row[i])

                assert len(new_row) == len(row)

                return new_row

            return tighten(merge(tighten(row)))

        moves = {}

        moves['Left']  = lambda field:                              \

                [move_row_left(row) for row in field]

        moves['Right'] = lambda field:                              \

                invert(moves['Left'](invert(field)))

        moves['Up']    = lambda field:                              \

                transpose(moves['Left'](transpose(field)))

        moves['Down']  = lambda field:                              \

                transpose(moves['Right'](transpose(field)))

        if direction in moves:

            if self.move_is_possible(direction):

                self.field = moves[direction](self.field)

                self.spawn()

                return True

            else:

                return False

    def is_win(self):

        return any(any(i >= self.win_value for i in row) for row in self.field)

    def is_gameover(self):

        return not any(self.move_is_possible(move) for move in actions)

    def draw(self, screen):

        help_string1 = '(W)Up (S)Down (A)Left (D)Right'

        help_string2 = '     (R)Restart (Q)Exit'

        gameover_string = '           GAME OVER'

        win_string = '          YOU WIN!'

        def cast(string):

            screen.addstr(string + '\n')

        def draw_hor_separator():

            line = '+' + ('+------' * self.width + '+')[1:]

            separator = defaultdict(lambda: line)

            if not hasattr(draw_hor_separator, "counter"):

                draw_hor_separator.counter = 0

            cast(separator[draw_hor_separator.counter])

            draw_hor_separator.counter += 1

        def draw_row(row):

            cast(''.join('|{: ^5} '.format(num) if num > 0 else '|      ' for num in row) + '|')

        screen.clear()

        cast('SCORE: ' + str(self.score))

        if 0 != self.highscore:

            cast('HGHSCORE: ' + str(self.highscore))

        for row in self.field:

            draw_hor_separator()

            draw_row(row)

        draw_hor_separator()

        if self.is_win():

            cast(win_string)

        else:

            if self.is_gameover():

                cast(gameover_string)

            else:

                cast(help_string1)

        cast(help_string2)

    def spawn(self):

        new_element = 4 if randrange(100) > 89 else 2

        (i,j) = choice([(i,j) for i in range(self.width) for j in range(self.height) if self.field[i][j] == 0])

        self.field[i][j] = new_element

    def move_is_possible(self, direction):

        def row_is_left_movable(row):

            def change(i): # true if there'll be change in i-th tile

                if row[i] == 0 and row[i + 1] != 0: # Move

                    return True

                if row[i] != 0 and row[i + 1] == row[i]: # Merge

                    return True

                return False

            return any(change(i) for i in range(len(row) - 1))

        check = {}

        check['Left']  = lambda field:                              \

                any(row_is_left_movable(row) for row in field)

        check['Right'] = lambda field:                              \

                 check['Left'](invert(field))

        check['Up']    = lambda field:                              \

                check['Left'](transpose(field))

        check['Down']  = lambda field:                              \

                check['Right'](transpose(field))

        if direction in check:

            return check[direction](self.field)

        else:

            return False

def main(stdscr):

    def init():

        #重置游戏棋盘

        game_field.reset()

        return 'Game'

    def not_game(state):

        #画出 GameOver 或者 Win 的界面

        game_field.draw(stdscr)

        #读取用户输入得到action，判断是重启游戏还是结束游戏

        action = get_user_action(stdscr)

        responses = defaultdict(lambda: state) #默认是当前状态，没有行为就会一直在当前界面循环

        responses['Restart'], responses['Exit'] = 'Init', 'Exit' #对应不同的行为转换到不同的状态

        return responses[action]

    def game():

        #画出当前棋盘状态

        game_field.draw(stdscr)

        #读取用户输入得到action

        action = get_user_action(stdscr)

        if action == 'Restart':

            return 'Init'

        if action == 'Exit':

            return 'Exit'

        if game_field.move(action): # move successful

            if game_field.is_win():

                return 'Win'

            if game_field.is_gameover():

                return 'Gameover'

        return 'Game'

    state_actions = {

            'Init': init,

            'Win': lambda: not_game('Win'),

            'Gameover': lambda: not_game('Gameover'),

            'Game': game

        }

    curses.use_default_colors()

    game_field = GameField(win=32)

    state = 'Init'

    #状态机开始循环

    while state != 'Exit':

        state = state_actions[state]()

curses.wrapper(main)

License

本作品在 GFDL1.2 协议下授权使用