python实现翻转棋游戏（othello）

利用上一篇的框架，再写了个翻转棋的程序，为了调试minimax算法，花了两天的时间。

几点改进说明：

• 拆分成四个文件：board.py，player.py，ai.py，othello.py。使得整个结构更清晰，更通用，更易于维护。

• AI 的水平跟 minimax 的递归深度，以及评价函数有关。基于此，我把 minimax 和评价函数都放到 AI 类里面

• AIPlayer 使用了多重继承。继承了 Player 与 AI 两个类

• Game 类中把原run函数里的生成两个玩家的部分提出来，写成一个函数make_two_players，使得 run函数结构更清晰

• AI 玩家等级不要选择 0：beginer。会报错，还没调试好

board.py

'''
作者：hhh5460
时间：2017年7月1日
'''

class Board(object):
def __init__(self):
 self.empty = '.'
 self._board = [[self.empty for _ in range(8)] for _ in range(8)] # 规格：8*8
 self._board[3][4], self._board[4][3] = 'X', 'X'
 self._board[3][3], self._board[4][4] = 'O', 'O'

# 增加 Board[][] 索引语法
def __getitem__(self, index):
 return self._board[index]

# 打印棋盘
def print_b(self):
 board = self._board
 print(' ', ' '.join(list('ABCDEFGH')))
 for i in range(8):
  print(str(i+1),' '.join(board[i]))

# 棋局终止
def teminate(self):
 list1 = list(self.get_legal_actions('X'))
 list2 = list(self.get_legal_actions('O'))
 return [False, True][len(list1) == 0 and len(list2) == 0]

# 判断赢家
def get_winner(self):
 s1, s2 = 0, 0
 for i in range(8):
  for j in range(8):
   if self._board[i][j] == 'X':
    s1 += 1
   if self._board[i][j] == 'O':
    s2 += 1
 if s1 > s2:
  return 0 # 黑胜
 elif s1 < s2:
  return 1 # 白胜
 elif s1 == s2:
  return 2 # 平局
# 落子
def _move(self, action, color):
 x,y = action
 self._board[x][y] = color

return self._flip(action, color)

# 翻子（返回list）
def _flip(self, action, color):
 flipped_pos = []

for line in self._get_lines(action):
  for i,p in enumerate(line):
   if self._board[p[0]][p[1]] == self.empty:
    break
   elif self._board[p[0]][p[1]] == color:
    flipped_pos.extend(line[:i])
    break

for p in flipped_pos:
  self._board[p[0]][p[1]] = color

return flipped_pos

# 撤销
def _unmove(self, action, flipped_pos, color):
 self._board[action[0]][action[1]] = self.empty

uncolor = ['X', 'O'][color=='X']
 for p in flipped_pos:
  self._board[p[0]][p[1]] = uncolor

# 生成8个方向的下标数组，方便后续操作
def _get_lines(self, action):
 '''说明：刚开始我是用一维棋盘来考虑的，后来改为二维棋盘。偷懒，不想推倒重来，简单地修改了一下'''
 board_coord = [(i,j) for i in range(8) for j in range(8)] # 棋盘坐标

r,c = action
 ix = r*8 + c
 r, c = ix//8, ix％8
 left = board_coord[r*8:ix] # 要反转
 right = board_coord[ix+1:(r+1)*8]
 top = board_coord[c:ix:8] # 要反转
 bottom = board_coord[ix+8:8*8:8]

if r <= c:
  lefttop = board_coord[c-r:ix:9] # 要反转
  rightbottom = board_coord[ix+9:(7-(c-r))*8+7+1:9]
 else:
  lefttop = board_coord[(r-c)*8:ix:9] # 要反转
  rightbottom = board_coord[ix+9:7*8+(7-(c-r))+1:9]

if r+c<=7:
  leftbottom = board_coord[ix+7:(r+c)*8:7]
  righttop = board_coord[r+c:ix:7] # 要反转
 else:
  leftbottom = board_coord[ix+7:7*8+(r+c)-7+1:7]
  righttop = board_coord[((r+c)-7)*8+7:ix:7] # 要反转

# 有四个要反转，方便判断
 left.reverse()
 top.reverse()
 lefttop.reverse()
 righttop.reverse()
 lines = [left, top, lefttop, righttop, right, bottom, leftbottom, rightbottom]
 return lines

# 检测，位置是否有子可翻
def _can_fliped(self, action, color):
 flipped_pos = []

for line in self._get_lines(action):
  for i,p in enumerate(line):
   if self._board[p[0]][p[1]] == self.empty:
    break
   elif self._board[p[0]][p[1]] == color:
    flipped_pos.extend(line[:i])
    break
 return [False, True][len(flipped_pos) > 0]

# 合法走法
def get_legal_actions(self, color):
 uncolor = ['X', 'O'][color=='X']
 uncolor_near_points = [] # 反色邻近的空位

board = self._board
 for i in range(8):
  for j in range(8):
   if board[i][j] == uncolor:
    for dx,dy in [(-1,0),(-1,1),(0,1),(1,1),(1,0),(1,-1),(0,-1)]:
     x, y = i+dx, j+dy
     if 0 <= x <=7 and 0 <= y <=7 and board[x][y] == self.empty and (x, y) not in uncolor_near_points:
      uncolor_near_points.append((x, y))
 for p in uncolor_near_points:
  if self._can_fliped(p, color):
   yield p

# 测试
if __name__ == '__main__':
board = Board()
board.print_b()
print(list(board.get_legal_actions('X')))

player.py

from ai import AI

'''
作者：hhh5460
时间：2017年7月1日
'''

# 玩家
class Player(object):
def __init__(self, color):
 self.color = color

# 思考
def think(self, board):
 pass

# 落子
def move(self, board, action):
 flipped_pos = board._move(action, self.color)
 return flipped_pos

# 悔子
def unmove(self, board, action, flipped_pos):
 board._unmove(action, flipped_pos, self.color)

# 人类玩家
class HumanPlayer(Player):
def __init__(self, color):
 super().__init__(color)

def think(self, board):
 while True:
  action = input("Turn to '{}'. \nPlease input a point.(such as 'A1'): ".format(self.color)) # A1~H8
  r, c = action[1], action[0].upper()
  if r in '12345678' and c in 'ABCDEFGH': # 合法性检查1
   x, y = '12345678'.index(r), 'ABCDEFGH'.index(c)
   if (x,y) in board.get_legal_actions(self.color): # 合法性检查2
    return x, y

# 电脑玩家（多重继承）
class AIPlayer(Player, AI):

def __init__(self, color, level_ix=0):
 super().__init__(color)    # init Player
 super(Player, self).__init__(level_ix) # init AI

def think(self, board):
 print("Turn to '{}'. \nPlease wait a moment. AI is thinking...".format(self.color))
 uncolor = ['X','O'][self.color=='X']
 opfor = AIPlayer(uncolor) # 假想敌，陪练
 action = self.brain(board, opfor, 4)
 return action

ai.py

import random

'''
作者：hhh5460
时间：2017年7月1日
'''

class AI(object):
'''
三个水平等级：初级（beginner）、中级（intermediate）、高级（advanced）
'''
def __init__(self, level_ix =0):
 # 玩家等级
 self.level = ['beginner','intermediate','advanced'][level_ix]
 # 棋盘位置权重，参考：https://github.com/k-time/ai-minimax-agent/blob/master/ksx2101.py
 self.board_weights = [
  [120, -20, 20, 5, 5, 20, -20, 120],
  [-20, -40, -5, -5, -5, -5, -40, -20],
  [ 20, -5, 15, 3, 3, 15, -5, 20],
  [ 5, -5, 3, 3, 3, 3, -5, 5],
  [ 5, -5, 3, 3, 3, 3, -5, 5],
  [ 20, -5, 15, 3, 3, 15, -5, 20],
  [-20, -40, -5, -5, -5, -5, -40, -20],
  [120, -20, 20, 5, 5, 20, -20, 120]
 ]

# 评估函数（仅根据棋盘位置权重）
def evaluate(self, board, color):
 uncolor = ['X','O'][color=='X']
 score = 0
 for i in range(8):
  for j in range(8):
   if board[i][j] == color:
    score += self.board_weights[i][j]
   elif board[i][j] == uncolor:
    score -= self.board_weights[i][j]
 return score

# AI的大脑
def brain(self, board, opponent, depth):
 if self.level == 'beginer':   # 初级水平
  _, action = self.randomchoice(board)
 elif self.level == 'intermediate': # 中级水平
  _, action = self.minimax(board, opponent, depth)
 elif self.level == 'advanced':  # 高级水平
  _, action = self.minimax_alpha_beta(board, opponent, depth)
 assert action is not None, 'action is None'
 return action

# 随机选（从合法走法列表中随机选）
def randomchoice(self, board):
 color = self.color
 action_list = list(board.get_legal_actions(color))
 return None, random.choice(action_list)

# 极大极小算法，限制深度
def minimax(self, board, opfor, depth=4): # 其中 opfor 是假想敌、陪练
 '''参考：https://github.com/k-time/ai-minimax-agent/blob/master/ksx2101.py'''
 color = self.color

if depth == 0:
  return self.evaluate(board, color), None

action_list = list(board.get_legal_actions(color))
 if not action_list:
  return self.evaluate(board, color), None

best_score = -100000
 best_action = None

for action in action_list:
  flipped_pos = self.move(board, action) # 落子
  score, _ = opfor.minimax(board, self, depth-1) # 深度优先，轮到陪练
  self.unmove(board, action, flipped_pos) # 回溯

score = -score
  if score > best_score:
   best_score = score
   best_action = action

return best_score, best_action

# 极大极小算法，带alpha-beta剪枝
def minimax_alpha_beta(self, board, opfor, depth=8, my_best=-float('inf'), opp_best=float('inf')):
 '''参考：https://github.com/k-time/ai-minimax-agent/blob/master/ksx2101.py'''
 color = self.color

if depth == 0:
  return self.evaluate(board, color), None

action_list = list(board.get_legal_actions(color))
 if not action_list:
  return self.evaluate(board, color), None

best_score = my_best
 best_action = None

for action in action_list:
  flipped_pos = self.move(board, action) # 落子
  score, _ = opfor.minimax_alpha_beta(board, self, depth-1, -opp_best, -best_score) # 深度优先，轮到陪练
  self.unmove(board, action, flipped_pos) # 回溯

score = -score
  if score > best_score:
   best_score = score
   best_action = action

if best_score > opp_best:
   break

return best_score, best_action

othello.py

from board import Board
from player import HumanPlayer, AIPlayer

'''
作者：hhh5460
时间：2017年7月1日
'''

# 游戏
class Game(object):
def __init__(self):
 self.board = Board()
 self.current_player = None

# 生成两个玩家
def make_two_players(self):
 ps = input("Please select two player's type:\n\t0.Human\n\t1.AI\nSuch as:0 0\n:")
 p1, p2 = [int(p) for p in ps.split(' ')]
 if p1 == 1 or p2 == 1: # 至少有一个AI玩家
  level_ix = int(input("Please select the level of AI player.\n\t0: beginner\n\t1: intermediate\n\t2: advanced\n:"))
  if p1 == 0:
   player1 = HumanPlayer('X')
   player2 = AIPlayer('O', level_ix)
  elif p2 == 0:
   player1 = AIPlayer('X', level_ix)
   player2 = HumanPlayer('O')
  else:
   player1 = AIPlayer('X', level_ix)
   player2 = AIPlayer('O', level_ix)
 else:
  player1, player2 = HumanPlayer('X'), HumanPlayer('O') # 先手执X，后手执O

return player1, player2

# 切换玩家（游戏过程中）
def switch_player(self, player1, player2):
 if self.current_player is None:
  return player1
 else:
  return [player1, player2][self.current_player == player1]

# 打印赢家
def print_winner(self, winner): # winner in [0,1,2]
 print(['Winner is player1','Winner is player2','Draw'][winner])

# 运行游戏
def run(self):
 # 生成两个玩家
 player1, player2 = self.make_two_players()

# 游戏开始
 print('\nGame start!\n')
 self.board.print_b() # 显示棋盘
 while True:
  self.current_player = self.switch_player(player1, player2) # 切换当前玩家

action = self.current_player.think(self.board) # 当前玩家对棋盘进行思考后，得到招法

if action is not None:
   self.current_player.move(self.board, action) # 当前玩家执行招法，改变棋盘

self.board.print_b() # 显示当前棋盘

if self.board.teminate(): # 根据当前棋盘，判断棋局是否终止
   winner = self.board.get_winner() # 得到赢家 0,1,2
   break

self.print_winner(winner)
 print('Game over!')

self.board.print_history()

if __name__ == '__main__':
Game().run()

效果图

来源：https://www.cnblogs.com/hhh5460/p/7102676.html