Python - turtle - Barnsley Fern

#
# Barnsley Fern
#
# https://en.wikipedia.org/wiki/Barnsley_fern
#

import random
import turtle

turtle.setup(850, 850)
turtle.penup()
turtle.speed(0)
turtle.tracer(0, 0)

x = 0
y = 0

for i in range(1, 16000):
    r = random.uniform(0, 1)

    if r < 0.1:
        temp_x = 0
        temp_y = 0.16 * y
        x = temp_x
        y = temp_y
    elif r < 0.80:
        temp_x =  0.85 * x + 0.04 * y
        temp_y = -0.04 * x + 0.85 * y + 1.6
        x = temp_x
        y = temp_y
    elif r < 0.93:
        temp_x =  0.20 * x + -0.26 * y
        temp_y =  0.23 * x +  0.22 * y + 1.6
        x = temp_x
        y = temp_y
    else:
        temp_x = -0.15 * x + 0.28 * y
        temp_y =  0.26 * x + 0.24 * y + 0.44
        x = temp_x
        y = temp_y

    turtle.goto(x*80, y*80 - 400) # move down -400 pixels
    turtle.dot(2, 'green')

turtle.hideturtle()
turtle.update() # need to run hideturtle()
turtle.mainloop()