I'm working on a text-based tic-tac-toe game, mostly for fun and because I'm learning programming. I would appreciate any comments you could give me to improve it.
Main structure:
It uses a Board class for all the games. It's initialized with an empty tic-tac-toe board implemented using numpy arrays. It has views to handle the rows, columns and diagonals directly. It also initializes some other variables (player token, current game turns, etc.).
Most of the the functions are helpers to handle the different moves performed by the computer (completing triples, filling diagonal cases, etc.). The game loop is performed by the play function, which calls the other two main functions: computer_turn and user_turn.
Code:
from itertools import cycle
from random import shuffle
import numpy as np
### TODO:
# - 2 player mode.
# - Choose player/cpu token.
class NoMove(Exception):
pass
class Board:
players = cycle('xo')
def __init__(self):
self.board = np.array([['', '', ''], ['', '', ''], ['', '', '']])
self.rows = [self.board[0], self.board[1], self.board[2]]
self.columns = [self.board[:, 0], self.board[:, 1], self.board[:, 2]]
# Top to bottom, left to right diagonal
self.diag0 = np.einsum('ii->i', self.board)
# To to bottom, right to left diagonal
self.diag1 = np.einsum('ii->i', np.fliplr(self.board))
self.diags = [self.diag0, self.diag1]
self.player = next(Board.players)
self.user_score = 0
self.computer_score = 0
self.turns = 0
def check_winner(self, player=None):
"""
player: The token to check
Checks if a row, column or diagonal is filled with 'player' token.
If no 'player' token is given, uses curren self.player token.
Returns True if condition is valid. False otherwise.
"""
if not player:
player = self.player
# Horizontal win
for i in range(3):
if np.sum(self.rows[i] == player) == 3:
print('Horizontal check')
return True
# Vertical win
for j in range(3):
if np.sum(self.columns[j] == player) == 3:
print('Vertical check')
return True
# Diagonal win
for d in range(2):
if np.sum(self.diags[d] == player) == 3:
print('Diagonal check')
return True
return False
def fill_next(self):
"""
Fills the next empty case with self.player token.
"""
for i in range(3):
for j in range(3):
if not self.board[i][j]:
self.board[i][j] = self.player
return None
def fill_corner(self):
"""
Chooses one corner randomly.
If it's empty, fills it with self.player token.
Raises NoMove exception if not possible for all corners.
"""
random_corners = list(range(4))
shuffle(random_corners)
for i in random_corners:
if i == 0 and not self.board[0][0]:
self.board[0][0] = self.player
break
elif i == 1 and not self.board[0][2]:
self.board[0][2] = self.player
break
elif i == 2 and not self.board[2][0]:
self.board[2][0] = self.player
break
elif i == 3 and not self.board[2][2]:
self.board[2][2] = self.player
break
else:
raise NoMove
def diagonal_free(self):
"""
If center case is free, will attempt to fill the diagonally opposed case
of a case already filled with self.player token.
Raises a NoMove exception if conditions aren't met.
"""
if not self.board[1][1]:
for d in range(2):
for filled, empty in [(0, 2), (2, 0)]:
if self.diags[d][filled] == self.player and \
not self.diags[d][empty]:
self.diags[d][empty] = self.player
return None
else:
raise NoMove
else:
raise NoMove
def complete_triple(self, target=None):
"""
target: A player token. If none is given, will use current
self.player token.
Scans rows, columns and diagonals for 2 occurrences of target token.
If 2 cases are filled with 'target', it will fill the remaining case
with target.
If no occurrences take place, raises NoMove exception.
"""
def try_fill(array3):
"""
array3: An array with 3 elements.
If two elements of the array are filled with 'target' token and
one is empty, fills the empty case with current self.player token.
Returns True if successful. False if not.
"""
if np.sum(array3 == target) == 2 and \
np.sum(array3 == '') == 1:
array3[array3 == ''] = self.player
return True
return False
if not target:
target = self.player
# Rows
for row in self.rows:
if try_fill(row):
return None
# Columns
for column in self.columns:
if try_fill(column):
return None
# Diagonals
for diagonal in self.diags:
if try_fill(diagonal):
return None
raise NoMove
def win_move(self):
"""
Searches for rows, columns and diagonals with 2 occurrences of
self.symbol and completes it to win.
If no occurrences take place, complete_triple raises NoMove exception.
"""
self.complete_triple()
return None
def avoid_losing(self):
"""
Searches for rows, columns and diagonals with 2 occurrences of
the adversary of self.player token.
Completes the empty case to avoid losing.
If no occurrences take place, raises NoMove exception.
"""
if self.player == 'x':
target = 'o'
else:
target = 'x'
self.complete_triple(target)
return None
def count_corners(self, target=None):
"""
Returns the number of corners occupied by the current
self.player token. (0 - 4)
"""
if not target:
target = self.player
return np.sum(self.board[[0, 0, -1, -1], [0, -1, 0, -1]] == target)
def defend_corner(self):
"""
Checks if the other player has filled one of the corners of the board.
Returns True or False.
"""
if self.player == 'x':
other_player = 'o'
else:
other_player = 'x'
return self.count_corners(other_player) >= 1
def scan_one(self, array3):
"""
array3: An array with 3 elements.
Scans if token self.token occupies one and only one token
in array3. All other cases must be empty.
Returns True if valid. If not, False.
"""
return np.sum(array3 == self.player) == 1 and \
np.sum(array3 == '') == 2
def fill_one(self, array3):
"""
array3: An array of 3 elements.
Fills the first empty case in array3 with self.player token.
Raise NoMove exception if not possible
"""
for i in range(3):
if not array3[i]:
array3[i] = self.player
return None
raise NoMove
def complete_second(self):
"""
Will scan rows, columns and diagonals (in that order)
with only one current player case filled and no cases filled
by the other player. It will then fill one of those cases.
Returns NoMove exception if no occurrence is possible.
"""
for i in range(3):
if self.scan_one(self.rows[i]):
self.fill_one(self.rows[i])
return None
for j in range(3):
if self.scan_one(self.columns[j]):
self.fill_one(self.columns[j])
return None
for diagonal in self.diags:
if self.scan_one(diagonal):
self.fill_one(diagonal)
return None
raise NoMove
def computer_turn(self):
"""
Attempts different moves.
If any move succeds, it returns None.
When a move fails, it raises a NoMove exception and
attempts the next move.
"""
self.turns +=1
if self.player == 'x':
other_player = 'o'
else:
other_player = 'x'
input('Computer turn... (Press any key to continue)')
# Starts by filling any of the corners.
if self.turns <= 2:
# If the other player started the game and filled
# any of the corners, fill the center case.
if self.turns == 2:
if self.defend_corner():
self.board[1][1] = self.player
return None
try:
self.fill_corner()
return None
except NoMove:
pass
# Attempts to win the game with a single move.
try:
self.win_move()
return None
except NoMove:
pass
# If the opponent is about to complete a triple, avoid it.
try:
self.avoid_losing()
return None
except NoMove:
pass
# Attempts filling the diagonally opposed case if
# the central case is empty.
try:
self.diagonal_free()
return None
except NoMove:
pass
# During mid game, attempts to continue filling corners.
# First verifies that some corners are already filled by the player
# or that the opponent hasn't filled the corners already so that
# it's a worthy move.
if (self.turns <= 4 and self.count_corners(other_player) != 2) or \
self.count_corners() >= 2:
try:
self.fill_corner()
return None
except NoMove:
pass
# If no other option, will complete any row/column/diagonal
# that has one player token and two empty cases.
try:
self.complete_second()
return None
except NoMove:
pass
# If no other possible options, fill any empty case.
self.fill_next()
return None
def get_index(self, text):
"""
Will prompt the player for a row or column index.
Returns an integer index between 0 - 2.
"""
index = 0
while True:
index = input("Choose a {} (0 - 2)\n".format(text))
try:
index = int(index)
except ValueError:
print('Please enter a number')
continue
if index > 2:
print('Invalid input. Possible values: 0 - 2')
else:
break
return index
def try_case(self, i, j):
"""
Will atempt filling the case[i][j].
Returns True on success. False otherwise.
"""
if not self.board[i][j]:
self.board[i][j] = self.player
return True
return False
def user_turn(self):
"""
Prompts the user for a row and a column index.
Verifies case isn't filled.
"""
self.turns += 1
print('Your turn')
while True:
i = self.get_index('row')
j = self.get_index('column')
if self.try_case(i, j):
break
else:
print('Case is filled. Choose another one!')
return None
def play(self):
"""
Game loop.
Starts with computer turn.
Alternates turns between player/computer.
Verifies if there is a winner.
Verifies if there is a draw.
Starts new game alternating from last player.
"""
current_player = self.player
print('Welcome!')
self.print_score()
input('New game?\n(Press any key to continue)')
print(self)
while True:
current_player = self.player
if current_player == 'x':
self.computer_turn()
print(self)
else:
self.user_turn()
print(self)
if self.check_winner():
if current_player == 'x':
self.computer_win()
else:
self.player_win()
self.print_score()
self.reset()
print('New game')
print(self)
# Loser starts next game
self.player = next(Board.players)
elif self.endgame():
self.print_score()
print("It's a draw!")
input('Press any key to continue...')
self.reset()
print('New game')
print(self)
self.player = next(Board.players)
else:
self.player = next(Board.players)
def endgame(self):
"""
Checks if 9 turns of the game have elapsed.
"""
return self.turns == 9
def reset(self):
"""
Empties all board cases and sets turns to 0.
"""
self.board.fill('')
self.turns = 0
def computer_win(self):
"""
Prints computer winning message.
Increments computer score by one.
"""
print('Computer won!')
input('Press enter to continue...')
self.computer_score += 1
def player_win(self):
"""
Prints player winning message.
Increases player score.
"""
print('You win!')
input('Press enter to continue...')
self.user_score += 1
def print_score(self):
"""
Prints score
"""
print('Current score is:\n Player\t: {}\n CPU\t: {}'
.format(self.user_score,self.computer_score))
def __str__(self):
"""
Game board pretty printing.
"""
dash = '---'
counter = 0
board_str = ''
for row in self.board:
board_str += '{: ^5s}|{: ^5s}|{: ^5s}\n'\
.format(row[0], row[1], row[2])
if counter < 2:
counter += 1
board_str += '{0: ^5s}+{0: ^5s}+{0: ^5s}\n'.format(dash)
return board_str
board = Board()
board.play()
