200行Python代码实现2048

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200行Python代码实现2048

2048原版游戏地址：http://gabrielecirulli.github.io/2048
创造游戏文件2048.py
首先导入需要的包：

import curses
from random import randrange, choice
from collections import defaultdict

1.主逻辑

1.1 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))

1.2 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actionif 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]()

2.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]

3.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]

4.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

4.1 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.scoreself.score = 0self.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_rowdef merge(row): # 对邻近元素进行合并pair = Falsenew_row = []for i in range(len(row)):if pair:new_row.append(2 * row[i])self.score += 2 * row[i]pair = Falseelse:if i + 1 < len(row) and row[i] == row[i + 1]:pair = Truenew_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 Trueelse: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 Trueif row[i] != 0 and row[i + 1] == row[i]: # 可以合并return Truereturn Falsereturn 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

4.2 绘制游戏界面

（注：这一步是在棋盘内定义的）

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 = 0cast(separator[draw_hor_separator.counter])draw_hor_separator.counter += 1def 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('HIGHSCORE: ' + 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)

5.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actionaction = get_user_action(stdscr)if action == 'Restart':return 'Init'if action == 'Exit':return 'Exit'if game_field.move(action): # move successfulif 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=2048)state = 'Init'#状态机开始循环while state != 'Exit':state = state_actions[state]()

6.运行

填上最后一行代码：

curses.wrapper(main)

运行python 2048.py查看结果。

全部代码

#-*- coding:utf-8 -*-import curses
from random import randrange, choice # generate and place new tile
from collections import defaultdictletter_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 = heightself.width = widthself.win_value = winself.score = 0self.highscore = 0self.reset()def reset(self):if self.score > self.highscore:self.highscore = self.scoreself.score = 0self.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 togethernew_row = [i for i in row if i != 0]new_row += [0 for i in range(len(row) - len(new_row))]return new_rowdef merge(row):pair = Falsenew_row = []for i in range(len(row)):if pair:new_row.append(2 * row[i])self.score += 2 * row[i]pair = Falseelse:if i + 1 < len(row) and row[i] == row[i + 1]:pair = Truenew_row.append(0)else:new_row.append(row[i])assert len(new_row) == len(row)return new_rowreturn 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 Trueelse:return Falsedef 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 = 0cast(separator[draw_hor_separator.counter])draw_hor_separator.counter += 1def 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('HIGHSCORE: ' + 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_elementdef move_is_possible(self, direction):def row_is_left_movable(row): def change(i): # true if there'll be change in i-th tileif row[i] == 0 and row[i + 1] != 0: # Movereturn Trueif row[i] != 0 and row[i + 1] == row[i]: # Mergereturn Truereturn Falsereturn 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 Falsedef 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actionaction = get_user_action(stdscr)if action == 'Restart':return 'Init'if action == 'Exit':return 'Exit'if game_field.move(action): # move successfulif 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()# 设置终结状态最大数值为 2048game_field = GameField(win=2048)state = 'Init'#状态机开始循环while state != 'Exit':state = state_actions[state]()curses.wrapper(main)