Array of Stars
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Inspect this next example carefully and get it up and running. Notice that
there are embedded for-loops in this example.
<![CDATA[
#!/usr/bin/python
import turtle
t=turtle.Pen()
t.speed(10)
t.screen.bgcolor("green")
t.pencolor("black")
t.pensize(3)
for y in range(-80,82,40):
for x in range(-80,82,40):
t.penup()
t.setx(x)
t.sety(y)
t.pendown()
t.seth(72)
for s in range(5):
t.right(144)
t.forward(30)
turtle.mainloop()
]]>
Indenting is extremely important in Python. When it comes to for-loops
anything contained within a for-loop is indented below it. Therefore,
for s in range(5): gets executed for each iteration of
for x
in range(-80,82,40):, which in turn is executed during each iteration
of for y in range(-80,82,40):. How many stars are produced by the
sample program? That's how many times the for s in
range(5): loop
gets executed. Just for grins and giggles, change the 82 in the for-loops
for x and y to 80 and do a recount on the stars. Why does the number of
stars change?
ASSIGNMENT:
Experiment to figure out how to make stars with various numbers of points.
Try to make seven, ten, eleven, and twelve pointed stars. Is there a
difference in the way you go about making stars with odd and even numbers of
points?
Once you have spent at least fifteen minutes playing around with
multi-pointed stars and have successfully figured out how to make a seven
point star, continue to the next part of the assignment.
Your assignment is to make a 15x15 array of seven-pointed stars.
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