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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：
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。
本节实验中将学习和实践以下知识点：
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
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))
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：
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]()
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]
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]
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
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 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()
(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)))
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
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 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
（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]()
填上最后一行代码：
curses.wrapper(main)
运行看看吧！
$ python 2048.py
#-*- 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(