rule90.py

import os
import sys
import time

RULES = {'111': '0', '010': '0', '101': '0', '000': '0',
         '100': '1', '011': '1', '110': '1', '001': '1'}


def draw(state):
    def window(state, length=3):
        for i in range(1, len(state) - length + 2):
            yield state[i-1:i+length-1]

    while True:
        for s in state:
            if s == '1':
                sys.stdout.write('#')
            else:
                sys.stdout.write(' ')

        print()
        time.sleep(0.033)

        state = ''.join(RULES[triplet] for triplet in window(state))
        state = f'0{state}0'


if __name__ == '__main__':
    _, columns = os.popen('stty size', 'r').read().split()
    half = int(columns) // 2
    state = '0' * half + '1' + '0' * half

    draw(state)