matrix.py

import random

ai_marker = 'X'

matrix = [
    ['7', '8', '9'],
    ['4', '5', '6'],
    ['1', '2', '3']
]
marked_spots = []
tries = 0

while (tries != 1):
    location = random.choice(list(range(1, 9)))
    for i, row in enumerate(matrix):
        for j, value in enumerate(row):
            if (location != 'X') and (location != 'O') and (location not in marked_spots) and (value == location):
                matrix[i][j] = ai_marker
                marked_spots.append(location)
                tries += 1