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