Exercise 4.1.Download the code in this chapter from http://thinkpython. com/code/poLygon.py .
- Write appropriate docstrings for polygon, arc and circle.
- Draw a stack diagram that shows the state of the program while executing circle(bob, radius). You can do the arithmetic by hand or add printstatements to the code.
- The version of arcin Refactoring is not very accurate because the linear approximation of the circle is always outside the true circle. As a result, the turtle ends up a few units away from the correct destination. My solution shows a way to reduce the effect of this error. Read the code and see if it makes sense to you. If you draw a diagram, you might see how it works.
Exercise 4.2. Write an appropriately general set of functions that can draw flowers as in Figure 4.1.
Solution: http://thinkpython.com/code/flower.py,
also requires
http://thinkpython.com/code/poLygon.py.
Exercise 4.3.Write an appropriately general set of functions that can draw shapes as in Figure 4.2.
Solution: http://thinkpython.com/code/pie.py.
Exercise 4.4.The letters of the alphabet can be constructed from a moderate number of basic elements, like vertical and horizontal lines and a few curves. Design a font that can be drawn with a minimal number of basic elements and then write functions that draw letters of the alphabet.
You should write one function for each letter, with names draw_a, draw_b, etc., and put your functions in a file named letters.py. You can download a “turtle typewriter” from http://www.greenteapress.com/thinkpython/code/typewriter.py to help you test your code.
Solution: http://www.greenteapress.com/thinkpython/code/letters.py ,also requires http://thinkpython.com/ code/poLygon.py.
Exercise 4.5.Read about spirals at http://en.wikipedia.org/wiki/SpiraL ; then write a program that draws an Archimedian spiral (or one of the other kinds). Solution:http://thinkpython.com/code/spiraL.py.
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