life-v0.5_next_cell_state.py

#!/usr/bin/python3

"""
Author: Leo Vidarte <http://nerdlabs.com.ar>

This is free software,
you can redistribute it and/or modify it
under the terms of the GPL version 3
as published by the Free Software Foundation.

"""

"""
Las transiciones dependen del número de células vecinas vivas:

  * Una célula muerta con exactamente 3 células vecinas vivas "nace"
    (al turno siguiente estará viva).
  * Una célula viva con 2 ó 3 células vecinas vivas sigue viva.
  * En otro caso muere o permanece muerta (por "soledad" o "superpoblación").

"""


DEAD   = 0
ALIVE  = 1


def print_board(board):
    for row in board:
        print(' '.join(['.' if col == DEAD else '#' for col in row]))

def get_board_size(board):
    width  = len(board[0]) # explícito mejor que implícito
    height = len(board)
    return (width, height)

def count_neighbors_alive(cell_pos, board):
    x_center, y_center = cell_pos
    width, height = get_board_size(board)

    x_left  = x_center-1 if x_center-1 >= 0     else width-1
    x_right = x_center+1 if x_center+1 < width  else 0
    y_up    = y_center-1 if y_center-1 >= 0     else height-1
    y_down  = y_center+1 if y_center+1 < height else 0

    return (board[y_up][x_left],
            board[y_up][x_center],
            board[y_up][x_right],
            board[y_center][x_left],
            board[y_center][x_right],
            board[y_down][x_left],
            board[y_down][x_center],
            board[y_down][x_right]).count(ALIVE)

def get_next_cell_state(cell_state, neighbors_alive):
    if (cell_state == DEAD and neighbors_alive == 3) or \
       (cell_state == ALIVE and neighbors_alive in (2, 3)):
        return ALIVE
    else:
        return DEAD


if __name__ == '__main__':

    # Glider
    board = [
        [0, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 1, 0, 0, 0, 0],
        [0, 0, 0, 0, 1, 0, 0, 0],
        [0, 0, 1, 1, 1, 0, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0],
        [0, 0, 0, 0, 0, 0, 0, 0],
    ]

    print_board(board)

    width, height = get_board_size(board)

    for x in range(width):
        for y in range(height):
            cell_pos = (x, y)
            cell_state = board[y][x] # alive or dead
            neighbors_alive = count_neighbors_alive(cell_pos, board)
            cell_next_state = get_next_cell_state(cell_state, neighbors_alive)
            print(cell_pos, neighbors_alive, cell_state, cell_next_state)