"""This module contains a code example related to
Think Python, 2nd Edition
by Allen Downey
http://thinkpython2.com
Copyright 2015 Allen Downey
License: http://creativecommons.org/licenses/by/4.0/
"""
from __future__ import print_function, division
import turtle
def draw_spiral(t, n, length=3, a=0.1, b=0.0002):
"""Draws an Archimedian spiral starting at the origin.
Args:
n: how many line segments to draw
length: how long each segment is
a: how loose the initial spiral starts out (larger is looser)
b: how loosly coiled the spiral is (larger is looser)
http://en.wikipedia.org/wiki/Spiral
"""
theta = 0.0
for i in range(n):
t.fd(length)
dtheta = 1 / (a + b * theta)
t.lt(dtheta)
theta += dtheta
# create the world and bob
bob = turtle.Turtle()
draw_spiral(bob, n=1000)
turtle.mainloop()