CSSE 120 -- Intro. to Software Development

Homework 4

A great place and time to do these exercises are the CSSE lab F-217 during student assistant hours, since you can get immediate help from the lab assistant.

1. Complete the assigned reading for the next session, Zelle, § 4.1 - 4.5.
2. (31 pts) Complete the ANGEL quiz over this reading. You'll find this on the course ANGEL page, under Lessons → Homework → Homework 4 → String Manipulation
   

3. (10 pts) Complete Programming Exercise 3.2 on page 72 of Zelle. Include appropriate comments. Name your program area.py. Your program should:

   1. Prompt the user to enter the diameter and price of the pizza.
   2. Use the math module to get the value of pi.
   3. Display the cost per square inch, with a descriptive label.

   Upload your area.py file to the Area dropbox in the Homework 4 folder.

4. (14 points) Using range. Write a Python range expression for each of the following lists. You should write your expressions in a new file, rangeAndList.py, in IDLE, using print statements to print the answers. Answers to the first two are given as examples.
   1. [0, 1, 2, 3, 4, 5]
      Answer: print "4a.", range(6)
   2. [2, 3, 4, 5, 6, 7]
      Answer: print "4b.", range(2, 8)
   3. [-2, -1, 0, 1, 2]
   4. [1, 3, 5, 7, 9]
   5. [1, 4]
   6. [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]
   7. [2, 1, 0, -1, -2] 
   
   

5. (14 more points) Manipulating Lists. Continuing with the rangeAndList.py file you created for the previous problem, add the following line of code:

   myList = [3, 6, 8, 11, 7, 4, 5, 9, 10, 0, 2]

   Now add statements to your program that print each of the following numbers or lists using expressions involving myList. Again, a couple of examples are given.

   1. 3
      Answer: print "5a.", myList[0]
   2. [3, 6, 8]
      Answer: print "5b.", myList[:3]
   3. [8, 11, 7, 4]
   4. 2 (i.e., the last element of myList )
   5. [0, 2]
   6. The position of 4 in myList.
   7. The length of myList.

   Upload the file containing your answers to this problem and the previous one to the RangeAndList dropbox in the Homework 4 folder. on ANGEL.

6. (45 points - 15 for each shape) Some Geometry with Lists. For this problem you will draw 3 shapes (also see pictures below):

   • A "pizza pie" with a given number of slices
   • An inscribed regular polygon with a given number of sides
   • An inscribed star, generated by connecting every other vertex of a regular polygon

   Start with this geometry.py file. Note that it:

   • Specifies 3 circles, each with radius 150.
   • Asks the user for a small odd integer called number.
   • Makes vertices be a list of number vertices on each of the three circles, respectively.

   Your job is to make the 3 shapes appear, per the TODO's in the geometry.py file. You MUST use the vertices list in a meaningful way to get credit. The pictures below show what the display of your programs should look like for a couple of cases.

   Examples when number is 5:

   

   Examples when number is 7:

   

   Upload your geometry.py file to the Geometry Graphics Program dropbox in the Homework 4 folder.

7. Bonus (10 points). In the previous problem, we gave you some vertices-building code:

   vertices = []
   for i in range(number):
   	x = radius * cos(2 * pi * i / number) + centerX
   	y = radius * sin(2 * pi * i / number) + centerY
   	vertices.append(Point(x, y))
   

   Your job for this bonus problem is to replace the above code with a single-line list comprehension statement, that builds the list of vertices.
   • You'll get credit for this problem if the 3 occurences of the above code in your geometry.py file are correct list comprehensions. No need to submit another file.
   • The term "list comprehension" is not mentioned in the Zelle textbook, but you can find it in today's PowerPoint slides on-line.  Further examples are available in the Python tutorial at http://docs.python.org/tut/node7.html#SECTION007140000000000000000
8. Bonus (10 points). Animate one or more of your figures from the pizza/polygon/star problem above.
   • There are many ways to interpret what it means to animate those figures. Use any interpretation you like -- if it animates in some way, you get the bonus credit!
   • Note that you don't have to animate all three figures (although you are welcome to try to do so -- probably hard). Animating just one earns you the bonus credit!
9. The Python Package Index, a repository of extensions to Python, is often called the Cheese Shop. Watch this bizarre video to see where the reference comes from.