Noughts and Crosses game in Python

Question

I wrote a two player Noughts and Crosses game in Python 3, and came here to ask how I can improve this code.

import random
cell = ['1', '2', '3', '4', '5', '6', '7', '8', '9']
board = '\n\t ' + cell[0] + ' | ' + cell[1] + ' | ' + cell[2] + '\n\t-----------\n\t ' + cell[3] + ' | ' + cell[4] + ' | ' + cell[5] + '\n\t-----------\n\t ' + cell[6] + ' | ' + cell[7] + ' | ' + cell[8]
def owin(cell):
    return cell[0] == cell[1] == cell[2] == 'O' or cell[3] == cell[4] == cell[5] == 'O' or cell[6] == cell[7] == cell[8] == 'O' or cell[0] == cell[3] == cell[6] == 'O' or cell[1] == cell[4] == cell[7] == 'O' or cell[2] == cell[5] == cell[8] == 'O' or cell[0] == cell[4] == cell[8] == 'O' or cell[2] == cell[4] == cell[6] == 'O'
def xwin(cell):
    return cell[0] == cell[1] == cell[2] == 'X' or cell[3] == cell[4] == cell[5] == 'X' or cell[6] == cell[7] == cell[8] == 'X' or cell[0] == cell[3] == cell[6] == 'X' or cell[1] == cell[4] == cell[7] == 'X' or cell[2] == cell[5] == cell[8] == 'X' or cell[0] == cell[4] == cell[8] == 'X' or cell[2] == cell[4] == cell[6] == 'X'
def tie(cell):
    return cell[0] in ('O', 'X') and cell[1] in ('O', 'X') and cell[2] in ('O', 'X') and cell[3] in ('O', 'X') and cell[4] in ('O', 'X') and cell[5] in ('O', 'X') and cell[6] in ('O', 'X') and cell[7] in ('O', 'X') and cell[8] in ('O', 'X')
print('\tNOUGHTS AND CROSSES\n\t\tBy Lewis Cornwall')
instructions = input('Would you like to read the instructions? (y/n)')
if instructions == 'y':
    print('\nEach player takes turns to place a peice on the following grid:\n\n\t 1 | 2 | 3\n\t-----------\n\t 4 | 5 | 6\n\t-----------\n\t 7 | 8 | 9\n\nBy inputing a vaule when prompted. The first to 3 peices in a row wins.')
player1 = input('Enter player 1\'s name: ')
player2 = input('Enter player 2\'s name: ')
print(player1 + ', you are O and ' + player2 + ', you are X.')
nextPlayer = player1
while not(owin(cell) or xwin(cell)) and not tie(cell):
    print('This is the board:\n' + board)
    if nextPlayer == player1:
        move = input('\n' + player1 + ', select a number (1 - 9) to place your peice: ')
        cell[int(move) - 1] = 'O'
        board = '\n\t ' + cell[0] + ' | ' + cell[1] + ' | ' + cell[2] + '\n\t-----------\n\t ' + cell[3] + ' | ' + cell[4] + ' | ' + cell[5] + '\n\t-----------\n\t ' + cell[6] + ' | ' + cell[7] + ' | ' + cell[8]
        nextPlayer = player2
    else:
        move = input('\n' + player2 + ', select a number (1 - 9) to place your peice: ')
        cell[int(move) - 1] = 'X'
        board = '\n\t ' + cell[0] + ' | ' + cell[1] + ' | ' + cell[2] + '\n\t-----------\n\t ' + cell[3] + ' | ' + cell[4] + ' | ' + cell[5] + '\n\t-----------\n\t ' + cell[6] + ' | ' + cell[7] + ' | ' + cell[8]
        nextPlayer = player1
if owin(cell):
    print('Well done, ' + player1 + ', you won!')
elif xwin(cell):
    print('Well done, ' + player2 + ', you won!')
else:
    print('Unfortunately, neither of you were able to win today.')
input('Press <enter> to quit.')

Answer 1

Some notes:

cell = ['1', '2', '3', '4', '5', '6', '7', '8', '9']

Try to be less verbose: cell = "123456789".split() or cell = [str(n) for n in range(1, 10)]. Anyway, conceptually it's very dubious you initialize the board with its number instead of its state. Also, cell is not a good name, it's a collection, so cells.

board = '\n\t ' + cell[0] + ...

Don't write such a long lines, split them to fit a sound max width (80/100/...). Anyway, here the problem is that you shouldn't do that manually, do it programmatically (grouped from itertools):

board = "\n\t-----------\n\t".join(" | ".join(xs) for xs in grouped(cell, 3)) 

return cell[0] == cell1 == cell[2] == 'O' or cell[3] == cell[4] == cell[5] == 'O' or cell[6] == cell[7] == cell[8] == 'O' or cell[0] == cell[3] == cell[6] == 'O' or cell1 == cell[4] == cell[7] == 'O' or cell[2] == cell[5] == cell[8]== 'O

Ditto, use code:

groups = grouped(cell, 3)
any(all(x == 'O' for x in xs) for xs in [groups, zip(*groups)])

Note that you are not checking if a cell has already a piece.

Answer 2

Do not repeat code for each player. Instead, create functions with appropriate parameters. For example, instead of if owin(cell): you could have a win function that can be used like

if win(cell, 'O'):

or

if win(cell) == 'O':

Answer 3

You should change input to raw_input so that its automatically passed as a string.