turtle_test.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import turtle

STEP = 5

# This file renders a simple Heighway dragon. Liense: 3-clause BSD


def heighway_reverse(sequence):
    rev_sequence = []
    for turn in reversed(sequence):
        if turn == 'l':
            rev_sequence.append('r')
        elif turn == 'r':
            rev_sequence.append('l')

    return rev_sequence


def heighway_extend(sequence=[]):
    return sequence + ['r'] + heighway_reverse(sequence)


def draw_from_seq(sequence, step=STEP):
    for turn in sequence:
        turtle.fd(step)
        if turn == 'l':
            turtle.left(90)
        elif turn == 'r':
            turtle.right(90)
    turtle.fd(step)


def draw_n_iter(itercount=5, step=STEP):
    s = step
    seq = ['r']
    for _ in range(itercount):
        seq = heighway_extend(seq)

    draw_from_seq(seq, step=s)
    turtle.right(90)


turtle.speed(0)
draw_n_iter(11, step=STEP)
input()