Python练手项目（2）——200行实现2048小游戏

Python练手项目（2）——200行实现2048小游戏

感谢知乎上的知友提供的链接传送门，本例的代码转自“实验楼”网站的文档：实验楼链接

2048小游戏几乎所有人都知道，也有很多实现方式（C，Java等），相信读者们很多都自己写过。本例中将用Python实现，虽然在设计上（在我看来）不够好，不是很好的OO设计。但在这个例子中用到了很多Python的高级特性和好用的库，作为练习用也不错。

源码

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

# define all the actions that is valid to control
actions = ['Up', 'Left', 'Down', 'Right', 'Restart', 'Exit']
# define the corresponding code value of actions
letter_codes = [ord(ch) for ch in 'WASDRQwasdrq']
# zip the action with letter_codes
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 = 2048
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)]
# generate a new score at (i. j)
self.spawn()
self.spawn()

def move(self, direction):
def move_row_left(row):
def tighten(row):
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('HIGNSCORE: '+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):
if row[i] == 0 and row[i+1] != 0:
return True
if row[i] != 0 and row[i+1] == row[i]:
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():
# reset the game field
game_field.reset()
return 'Game'

def not_game(state):
# draw the UI of GameOver or Win
game_field.draw(stdscr)
# read what action user enters and judge whether restart or end the game
action = get_user_action(stdscr)
responses = defaultdict(lambda: state)  #default current state, stay loop when no action happen
responses['Restart'], responses['Exit'] = 'Init', 'Exit'  # translate action to state
return responses[action]

def game():
# draw the current state of game field
game_field.draw(stdscr)
# read user's action
action = get_user_action(stdscr)

if action == 'Restart':
return 'Init'
if action == 'Exit':
return 'Exit'
if game_field.move(action):
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'
# FSM start loop
while state != 'Exit':
state = state_actions[state]()

curses.wrapper(main)