Conway's Game of Life in the terminal

gol.py

import random
size = 20
#on = [(1,1),(1,2),(1,3)] #Blinker
#on = [(1,0),(2,1),(0,2),(1,2),(2,2)] #Glider
on = [(2,2),(3,2),(4,2),(5,2),(6,2),(7,2),(9,2),(10,2),(2,3),(3,3),(4,3),(5,3),(6,3),(7,3),(9,3),(10,3),(9,4),(10,4),(2,5),(3,5),(9,5),(10,5),(2,6),(3,6),(9,6),(10,6),(2,7),(3,7),(9,7),(10,7),(2,8),(3,8),(2,9),(3,9),(5,9),(6,9),(7,9),(8,9),(9,9),(10,9),(2,10),(3,10),(5,10),(6,10),(7,10),(8,10),(9,10),(10,10)]
#^ Galaxy
#on = [(24, 0), (22, 1), (24, 1), (12, 2), (13, 2), (20, 2), (21, 2), (34, 2), (35, 2), (11, 3), (15, 3), (20, 3), (21, 3), (34, 3), (35, 3), (0, 4), (1, 4), (10, 4), (16, 4), (20, 4), (21, 4), (0, 5), (1, 5), (10, 5), (14, 5), (16, 5), (17, 5), (22, 5), (24, 5), (10, 6), (16, 6), (24, 6), (11, 7), (15, 7), (12, 8), (13, 8)]
#^Glider gun, 60 iters (start at 60)
#on = [(random.randint(0,size),random.randint(0,size)) for _ in range(random.randint(1,size**2))] #Random

def iterate(on, size):
	u = [(x,y) for x in range(size) for y in range(size)]
	offsets = [(-1,-1),(-1,0),(-1,1),(0,-1),(0,1),(1,-1),(1,0),(1,1)]
	nb = []
	for x,y in u:
		r = [(x+i,y+j) for i,j in offsets]
		rc = [(x+i,y+j) for i,j in offsets]
		for i in rc:
			if i not in on:
				r.remove(i)
	
		r = len(r)
		nb.append(r)
	
	for i in range(len(u)):
		if nb[i] != 2 and nb[i] != 3:
			if u[i] in on:
				on.remove(u[i])
		
		if nb[i] == 3:
			if u[i] not in on:
				on.append(u[i])
	
	return on

u = [(y,x) for x in range(size) for y in range(size)]
i = 0
while True:
	print("Generation "+str(i))
	c = lambda x: "# " if x in on else ". "
	r = ""
	for j in range(1, len(u)+1):
		r += c(u[j-1])
		if j % size == 0:
			r += "\n"
		
	print(r)
	on = iterate(on, size)
	i += 1