i am trying to learn python and have been trying to programm a simple tictactoe game. Below is the code:
import random
class TicTacToe03:
def __init__(self):
# first, the board
self.board = self.board = [" ", " ", " ", " ", " ", " ", " ", " ", " "]
# then, the symbols the players will choose
self.playerSymbol = ""
self.aiSymbol = ""
# the game is always ongoing, unless somebody won
self.gameOngoing = True
# you also need to tell the ai how different conditions are evaluated
self.scoreBoard = {
self.playerSymbol: -10, # if the player wins, it is seen as smth bad from the ai
self.aiSymbol: 10,
"tie": 0
}
# every tictactoe game starts by drawing the board
def drawBoard(self):
print("""
{} | {} | {}
-----------
{} | {} | {}
-----------
{} | {} | {}
""".format(*self.board))
# then, eveybody chooses what the like
def chooseYourPlayer(self):
self.playerSymbol = input("choose your player X/O ").upper()
if self.playerSymbol == "X":
self.aiSymbol = "O"
else:
self.aiSymbol = "X"
# everybody has to behave and leave their turn when it's over
def nextPlayer(self, player):
if player == self.playerSymbol:
return self.aiSymbol
return self.playerSymbol
# ppl also have to be able to make moves
def move(self, player, index):
self.board[index] = player
# and find what moves they CAN make, so they don't override each-other
def availableMoves(self):
availableMoves = []
for fieldIndex in range(len(self.board)):
if self.board[fieldIndex] == " ":
availableMoves.append(fieldIndex) # yes, i append indexes, not empty fields
return availableMoves
def getMoves(self, player):
playerMoves = []
for fieldIndex in range(len(self.board)):
if self.board[fieldIndex] == player:
playerMoves.append(fieldIndex)
return playerMoves
# here is the algo to check who won, based on a set of winPos is subset of playerMoves
def won(self):
winningPositions = [{0, 1, 2}, {3, 4, 5}, {6, 7, 8},
{0, 4, 8}, {2, 4, 6}, {0, 3, 6},
{1, 4, 7}, {2, 5, 8}]
for player in ("X", "O"):
playerPositions = self.getMoves(player)
for position in winningPositions:
if position.issubset(playerPositions):
print(player + "wins")
self.gameOngoing = False
return player
if self.board.count(" ") == 0: # and this dude outside of the main loop
print("Guess it's a draw")
self.gameOngoing = False
return "tie"
def minimax(self, isMaximizing, player):
if not self.gameOngoing: # base in minimax: if this is an end-state, return it's evaluation
return self.scoreBoard[self.won()]
if isMaximizing:
bestScore = float("-Infinity") # the worst eval for max
for move in self.availableMoves():
self.move(player, move)
score = self.minimax(False, self.nextPlayer(player)) # you should pick the max of what your opponent chooses
self.move(" ", move)
bestScore = max(bestScore, score)
return bestScore
else:
bestScore = float("Infinity")
for move in self.availableMoves():
self.move(player, move)
score = self.minimax(True, self.nextPlayer(player))
self.move(" ", move)
bestScore = min(bestScore, score)
return bestScore
def findOptimalMove(self, player):
goldenMiddle = 0
choices = []
for move in self.availableMoves():
self.move(player, move)
score = self.minimax(True, player)
self.move(" ", move)
if score > goldenMiddle:
choices = [move] # this is a one-element list
break
elif score == goldenMiddle:
choices.append(move)
# here is the code block that mustn't be wrongly interpreted:
# the idea is: you choose a random element, from a ONE-ELEMENT list!!!
if len(choices) > 0:
return random.choice(choices)
else:
return random.choice(self.availableMoves())
def play(self):
self.chooseYourPlayer()
while self.gameOngoing:
personMove = int(input("Choose a position (1-9) "))
self.move(self.playerSymbol, personMove - 1)
self.drawBoard()
if not self.gameOngoing:
break
print("Computer choosing move...")
aiMove = self.findOptimalMove(self.aiSymbol)
self.move(self.aiSymbol, aiMove)
self.drawBoard()
print("Thanks for playing :)")
tictactoe = TicTacToe03()
tictactoe.play()
The game "works", as of it displays the fields of the user, however it won't show whether anybody won or not. As you can see, i tried implementing the simple minimax algorithm, but that doesn't work properly either, because the ai just chooses the next available field to go to and not the one it logically should.
As for the errors i am getting: i only got one once, after the board was full and it was the following: IndexError: Cannot choose from an empty sequence (on line 133).
I have also posted another version of this, where the "winning" issue is not present ( TicTacToe and Minimax ), but since nobody was answering that question, I thought it would be helpful asking again (sorry if i did anything wrong)
As always, I remain open to suggestions and ways to improve my code :)
