Quick Conway's Game of Life implementation

life.py

# You can run this on http://pythonsandbox.com/graphics

import sandbox
import time

canvas = sandbox.createCanvas()

def makegrid(width,height):
  return [[0 for y in range(0, height)] for x in range(0, width)]

def drawgrid(grid, cellwidth, cellheight):
  for x in range(0, len(grid)):
    for y in range(0, len(grid[x])):
      cx=x*cellwidth
      cy=y*cellheight
      c=grid[x][y]
      if c == 0:
        canvas.fillColor("Black")
      else:
	      canvas.fillColor("Green")
      canvas.fillRect((cx, cy), (cx+cellwidth,cy+cellheight))

def getcell(grid, x, y):
  if x < 0:
    x = len(grid)-1
  if y < 0:
    y = len(grid[0])-1
  if x >= len(grid):
    x = 0
  if y >= len(grid[x]):
    y = 0
  return grid[x][y]
  
def countneighbors(grid, x, y):
  neighbors = [(x-1,y-1),(x,y-1),(x+1,y-1),(x-1,y),(x+1,y),(x-1,y+1),(x,y+1),(x+1,y+1)]
  count = 0
  for n in neighbors:
		count = count + getcell(grid, n[0], n[1])
  return count

def liferule(grid, x, y):
  n = countneighbors(grid, x, y)
  if n <= 1:
    return 0
  if n >= 4:
    return 0
  if n == 3:
    return 1
  return getcell(grid, x, y)  

def nextgrid(grid):
  newgrid = makegrid(len(grid), len(grid[0]))
  for x in range(0, len(grid)): 
    for y in range(0, len(grid[x])):
      newgrid[x][y] = liferule(grid, x, y)
  return newgrid

g = makegrid(16, 16)
g[11][8] = 1
g[12][9] = 1
g[10][10] = 1
g[11][10] = 1
g[12][10] = 1

g[4][9] = 1
g[4][10] = 1
g[4][11] = 1
g[5][9] = 1
g[6][10] = 1


while True:
  drawgrid(g, 20, 20)
  g = nextgrid(g)
  time.sleep(0.06)