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v0.8.1
v0.8.1
https://github.com/python/cpython
Tip revision: 97fe9cfd9f81fe96a70e1ce80fce04b0c937bfac authored by Ćukasz Langa on 18 May 2020, 23:07:09 UTC
Python 3.9.0b1
Python 3.9.0b1
Tip revision: 97fe9cf
lindenmayer.py
#!/usr/bin/env python3
""" turtle-example-suite:
xtx_lindenmayer_indian.py
Each morning women in Tamil Nadu, in southern
India, place designs, created by using rice
flour and known as kolam on the thresholds of
their homes.
These can be described by Lindenmayer systems,
which can easily be implemented with turtle
graphics and Python.
Two examples are shown here:
(1) the snake kolam
(2) anklets of Krishna
Taken from Marcia Ascher: Mathematics
Elsewhere, An Exploration of Ideas Across
Cultures
"""
################################
# Mini Lindenmayer tool
###############################
from turtle import *
def replace( seq, replacementRules, n ):
for i in range(n):
newseq = ""
for element in seq:
newseq = newseq + replacementRules.get(element,element)
seq = newseq
return seq
def draw( commands, rules ):
for b in commands:
try:
rules[b]()
except TypeError:
try:
draw(rules[b], rules)
except:
pass
def main():
################################
# Example 1: Snake kolam
################################
def r():
right(45)
def l():
left(45)
def f():
forward(7.5)
snake_rules = {"-":r, "+":l, "f":f, "b":"f+f+f--f--f+f+f"}
snake_replacementRules = {"b": "b+f+b--f--b+f+b"}
snake_start = "b--f--b--f"
drawing = replace(snake_start, snake_replacementRules, 3)
reset()
speed(3)
tracer(1,0)
ht()
up()
backward(195)
down()
draw(drawing, snake_rules)
from time import sleep
sleep(3)
################################
# Example 2: Anklets of Krishna
################################
def A():
color("red")
circle(10,90)
def B():
from math import sqrt
color("black")
l = 5/sqrt(2)
forward(l)
circle(l, 270)
forward(l)
def F():
color("green")
forward(10)
krishna_rules = {"a":A, "b":B, "f":F}
krishna_replacementRules = {"a" : "afbfa", "b" : "afbfbfbfa" }
krishna_start = "fbfbfbfb"
reset()
speed(0)
tracer(3,0)
ht()
left(45)
drawing = replace(krishna_start, krishna_replacementRules, 3)
draw(drawing, krishna_rules)
tracer(1)
return "Done!"
if __name__=='__main__':
msg = main()
print(msg)
mainloop()