Succinct Game of Life

conway.py

# Jack Diederich wrote the advance function
# original code from http://pyvideo.org/video/880/stop-writing-classes

import collections
import curses
import gettext
import random
import signal
import sys
import time

from itertools import chain, count, ifilter, product

ROWS = 22
COLS = 40
ENTROPY = 100
REDRAW = 0.05

def not_origin(pt):
    return pt != (0,0)


def neighbors(point):
    x, y = point
    for dx, dy in ifilter(not_origin, product((0,1,-1),(0,1,-1))):
        yield x+dx, y+dy


def truncate(point):
    x, y = point
    return (x % ROWS, y % COLS)


def advance(board):
    newstate = set()
    recalc = board | set(chain(*map(neighbors, board)))
    for point in recalc:
        count = sum((neighbor in board) for neighbor in neighbors(point))
        if count == 3 or (count == 2 and point in board):
            newstate.add(point)
    return set(map(truncate, newstate))


def display(board):
    for x in range(ROWS):
        for y in range(COLS):
            screen.addstr(x, y, '*' if (x, y) in board else '.')
    screen.refresh()
    time.sleep(REDRAW)


def endwin(signum, frame):
    curses.endwin()
    sys.exit(0)


signal.signal(signal.SIGINT, endwin)
screen = curses.initscr()
board = set()
for _ in range(ENTROPY):
    x = random.randint(0, COLS)
    y = random.randint(0, ROWS)
    board.add((x, y))

prev = collections.deque(maxlen=2)
for i in count(1):
    display(board)
    prev.append(board)
    board = advance(board)
    if any(p == board for p in prev):
        break

plural = gettext.ngettext('', 's', i)
screen.addstr(ROWS,0,'Equillibrium in %d generation%s.\n' % (i, plural))
screen.getch()
curses.endwin()