a LOGO-style collatz path visualization

collatz_turtle.py

#!/bin/env python3

import turtle
from sys import argv
from random import randint


def collatz_path(n):
    path = [n]

    while n != 1:
        if n % 2 == 0:
            n = n // 2
        else:
            n = 3 * n + 1

        path.append(n)

    return path


def main():
    turtle.color('yellow', 'blue')
    turtle.begin_fill()
    path = None

    if len(argv) == 1:
        path = collatz_path(100) # if no command line argument is provided, use 100 as default n
    else:
        path = collatz_path(int(argv[1]))


    for step in path:
        turtle.forward(step % 120) # this is for scaling
        if randint(1, 10) % 2 == 0:
            turtle.left(step % 360)
        else:
            turtle.right(step % 360)

    turtle.end_fill()
    turtle.done()


if __name__=='__main__':
    main()