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Co-authored-by: Wulian <xiguawulian@gmail.com> Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>
60 lines
1.3 KiB
Python
60 lines
1.3 KiB
Python
"""turtledemo/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
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the current pen is cloned. So in the end
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there are 1024 turtles.
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"""
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from turtle import Turtle, mainloop
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from time import perf_counter as 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.getscreen().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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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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