File Content: tdemo_tree.py #! /usr/bin/env python """ turtle-example-suite: tdemo_tree.py Displays a 'breadth-first-tree' - in contrast to the classical Logo tree drawing programs, which use a depth-first-algorithm. Uses: (1) a tree-generator, where the drawing is quasi the side-effect, whereas the generator always yields None. (2) Turtle-cloning: At each branching point the current pen is cloned. So in the end there are 1024 turtles. """ from turtle import Turtle, mainloop from time import clock def tree(plist, l, a, f): """ plist is list of pens l is length of branch a is half of the angle between 2 branches f is factor by which branch is shortened from level to level.""" if l > 3: lst = [] for p in plist: p.forward(l) q = p.clone() p.left(a) q.right(a) lst.append(p) lst.append(q) for x in tree(lst, l*f, a, f): yield None def maketree(): p = Turtle() p.setundobuffer(None) p.hideturtle() p.speed(0) p.tracer(30,0) p.left(90) p.penup() p.forward(-210) p.pendown() t = tree([p], 200, 65, 0.6375) for x in t: pass print len(p.getscreen().turtles()) def main(): a=clock() maketree() b=clock() return "done: %.2f sec." % (b-a) if __name__ == "__main__": msg = main() print msg mainloop() Submit