Tic Tac Toe (Player vs Computer)

Question

I am looking on how I can improve my writing style and/or how to simplify how I write my code.

# USER: TCG
# Tic Tac Toe (User vs Computer)

import random

def place(num,x):
    # Returns all the moves made
    for i in range(len(x)):
        if x[i] == num:
            pos = x.index(num)
            return x[(pos + 1)]
    return str(num)

def print_grid(move,player,x):

    pos_list.extend([move,player])

    # Grid on which the player and computer play on            
    grid = ["","-------------\n",
        "|",place(1,pos_list),"|",place(2,pos_list),"|",place(3,pos_list),"|\n",
        "|---+---+---|\n",
        "|",place(4,pos_list),"|",place(5,pos_list),"|",place(6,pos_list),"|\n",
        "|---+---+---|\n",
        "|",place(7,pos_list),"|",place(8,pos_list),"|",place(9,pos_list),"|\n",
        "-------------\n"]
    if x == 2:
        # Only prints one the player has made a move
        print '\n', ' '.join(grid)

def winner(x,player,xx):

    # Checks if there is a winner (Really messy, could do with code simplifying)
    if ((1 in x and 4 in x and 7 in x)or(1 in x and 2 in x and 3 in x)or(2 in x and 5 in x and 8 in x)or(3 in x and 6 in x and 9 in x)or
    (4 in x and 5 in x and 6 in x)or(7 in x and 8 in x and 9 in x)or(1 in x and 5 in x and 9 in x)or(3 in x and 5 in x and 7 in x)):
    # If prevents the A.I part from printing the statemnt
        if xx <> 1:
            print '\n'*5,"\'%s\'" %player, "HAS WON!"
        return 1 == 1

def computer_AI_part(listx):
    global computer_move

    # Chceks all possible values which the player can and enter to win and blocks it
    for x in range(1,10):
        if x not in pos_list:
            listx.append(x)
            if (winner(listx,'Computer',1)) == True:
                del listx[-1]
                computer_move = x
                return 1
            del listx[-1]

def computer_and_player():
    global computer_move,pos_list,player_list,computer_list
    replay,draw = 0,0

    while True:

        # Replay's the game
        if replay == 1:
            restart = raw_input("Would you like to replay?: ")
            if restart == "yes":
                pass
            else:
                return
        else:
            print "\nTic Tac Toe - Computer vs You", '\n'*2,"Computer goes first\n"

        replay,computer_move,players_move,loop_count,pos_list,player_list,computer_list = 0,0,0,0,[],[],[]

        for each in "XXXXX":
            loop_count += 1

            # Computer's Move
            if computer_AI_part(computer_list) or computer_AI_part(player_list) == 1:
                pass     
            else:
                while True:
                    computer_move = random.randint(1,9)
                    if computer_move in pos_list:
                        continue
                    break
            computer_list.append(computer_move)
            # Prints Grid
            print_grid(computer_move,'O',2)

            if loop_count == 5:
                if winner(player_list,'player',2) == True or winner(computer_list,'Computer',2) == True:
                    pass
                else:
                    print "Match Was a draw!"
                replay = 1
                break

            # Checks winner
            if winner(computer_list,'Computer',2) == True:
                replay = 1
                break

            # Player's Move
            while True:
                try:
                    players_move = int(raw_input("\n\'%s\' Enter a value from the grid to plot your move: " %each))
                    if players_move in pos_list or players_move < 1 or players_move > 9:
                        print "Enter an available number that's between 1-9"
                        continue
                    break
                except:
                    print "Enter a number"

            player_list.append(players_move)
            # Sets player's move for printing
            print_grid(players_move,each,1)

            # Checks winner again
            if winner(player_list,'player',1) == True:
                print_grid(players_move,each,2)
                winner(player_list,'player',2)
                replay = 1
                break

if __name__ == "__main__":
    computer_and_player()

Update: new version

Answer 1

Here's a section of my game:

'X' Enter a value from the grid to plot your move: exit
Enter a number

'X' Enter a value from the grid to plot your move: leave
Enter a number

'X' Enter a value from the grid to plot your move: quit
Enter a number

'X' Enter a value from the grid to plot your move: ^CEnter a number

I was just trying to do a short test, and then go back to the code and make some more changes, but I couldn't get out of the program without finishing the game. It's good that you don't allow just anything, but ^C at least should let me get out.

---

Your place() function could be a little better by using enumerate():

def place(num,x):
    # Returns the value in x at position num
    for i, v in enumerate(x):
        if v == num:
            return x[(i + 1)]
    return str(num)

Your naming could still be improved. How is one to know that x is a list of positions and values? There's more that I would change, but I'll get to that below.

---

You have a function called print_grid that makes a move, too. Either create a new function to make the move or rename the current function to show that it has side effects.

---

Global variables are almost never necessary. If you are tempted, you might be better off either passing them as arguments or defining a class. In this case, I think a class would be the better option.

---

pos_list would be better off being a dictionary (of course with a different name). It would be {pos: value, pos: value, ...} instead of [pos, value, pos, value, ...]. That way, lookups are easier. For example, place() could be return x.get(num, str(num)) -- just one line!

---

Your grid is a little hard to follow. It would be better to have a template and fill it in:

    template = """
-------------
| {} | {} | {} |
|-----------|
| {} | {} | {} |
|-----------|
| {} | {} | {} |
--------------"""


    if x == 2:
        # Only prints if the player has made a move
        print template.format(*(place(num + 1, pos_list) for num in range(9)))

---

To be frank, I agree with you comment in winner() that the code is messy. I would define tuples of valid moves and see if any of them is a match:

def winner(x,player,xx):
    wins = ((1, 2, 3), (4, 5, 6), (7, 8, 9), # Horizontal
            (1, 4, 7), (2, 5, 8), (3, 6, 9), # Vertical
            (1, 5, 9), (3, 5, 7)) # Diagonal

    if any(all(pos in x for pos in win) for win in wins):
        if xx != 1:
            print '\n'*5, "'{}'".format(player), "HAS WON!"
        return True
    return False

I changed if xx <> 1: to if xx != 1: because it's a little more obvious what it means. In fact, Python 3 took out <> so you need to use !=. I also changed your print statement. You didn't need to escape ' because it was " that made it a string, so the ' wouldn't close the string. Also, while % is not officially deprecated, it is recommended to use .format(). While I was at it, I changed return 1 == 1 to return True. Why make Python evaluate an expression when you already know the answer?

---

def computer_AI_part(listx):

Every function does its part. You never need the word part in its name. Also, listx isn't very descriptive. What sort of list is it? Is it a list of moves?

while True:

    # Replay's the game
    if replay == 1:
        restart = raw_input("Would you like to replay?: ")
        if restart == "yes":
            pass
        else:
            return
    else:
        print "\nTic Tac Toe - Computer vs You", '\n'*2,"Computer goes first\n"

Since replay is always either 0 or 1, and since 0 is False and 1 is True, you can simply say if replay:. I would also change the logic slightly. If I typed y or Yes, your program would just exit. I would do something more like:

while True:

    # Replay's the game
    if replay:
        restart = raw_input("Would you like to replay?: ").lower()
        if restart in ("y", "yes"): 
            pass
        elif restart in ("n", "no"):
            return
        else:
            print "Say 'yes' or 'no'"
            continue
    else:
        print "\nTic Tac Toe - Computer vs You", '\n'*2,"Computer goes first\n"

It's only barely longer, and it is much more user-friendly.

---

replay,computer_move,players_move,loop_count,pos_list,player_list,computer_list = 0,0,0,0,[],[],[]

That's hard to read. If you want to put them all together like that, you should at least add some whitespace and put the different types on different lines:

replay, computer_move, players_move, loop_count = 0, 0, 0, 0
pos_list, player_list, computer_list = [], [], []

That's a lot easier to read.

---

if computer_move in pos_list:
    continue
break

Why not:

if computer_move not in pos_list:
    break

That's a little easier to understand.

---

 if winner(computer_list,'Computer',2) == True:

winner() already returns a boolean. Checking its equality with True is redundant because it will result ... in the same boolean.

---

except:
    print "Enter a number"

You have certain expectations for what errors could happen. I would change this to:

except ValueError:
    print "Enter a number"
except (EOFError, KeyboardInterrupt):
    exit()

Yay! That fixed my original problem of not being able to exit.

---

if __name__ == "__main__":
    computer_and_player()

Excellent! I can import your functions without running the whole code.