CS 151: Project 2

Title image Project 2
Spring 2020

Project 2: A Shape Collection

The goal of this assignment is to give you practice in creating and using functions and function parameters in Python. You'll continue to create shapes using turtle graphics, just like we did in lab.

The end result of the assignment should be a representation of a scene depicting something inspired by Sol Lewitt. The scene can be as simple or complex as you like. What is important is to properly structure your code and include good comments.

Remember that you need to write the code yourself. You can discuss the assignment and ideas regarding the assignment with others in natural language, but not Python. If you have questions about your Python code (other than very simple syntax questions), please ask one of the lab assistants or professors. Please see the syllabus for guidelines on collaboration and attribution.


  1. Set up your shape library code

    Make a copy of your lab2.py file and rename it shapelib.py (for "Shape Library").

    Delete the any code not inside a function from the file so that only the import statements and the functions remain. You should not have any top level code (code not inside a function) in the shapelib.py file. It is meant to form a library of shape-drawing functions that other code files will be able to import and use.

    Your first task is to create a main.py file that imports your shapelib.py functions. To do this, create a file called main.py in a text editor, and at the top (after your name, date, and description) put the following.

    import shapelib

    The import statement lets you call any functions in your shapelib.py file, such as block, using the syntax shapelib.block. You can rename shapelib as something more concise, if you wish in the import statement.

    In your main.py file, make a function called scene1. Put a single call to the scene1 function at the end of the file, followed by an input call.

    Write some python code in your scene1 function that calls some of the functions from your shapelib.py file to draw a simple image (like a few blocks). Note that to call a function from your shapelib file you have to prepend shapelib. in front of the function name. For example shapelib.block( 10, 10, 20, 30 ) would be how you would call the block function.

    You can run your main.py file using:

    python3 main.py

    You don't need to save this image, as you'll be replacing the code in the scene1 function later on.

  2. Write functions to draw basic shapes

    In your shapelib.py file, make 2 more functions for drawing basic shapes like the block function from lab. Basic shapes should take in at least an x location, y location, and size information. For example, you could make a triangle function or a hexagon function with the size value being the length of a side, in pixels. Put a print statement at the beginning of each function and test them out by calling the functions in your main.py function.

    Each of your shapes should draw properly no matter where it is drawn on the screen, what the size parameter is, or what the orientation of the turtle happens to be when the shape function executes. Test this out for all of your functions.

    In your report, include a picture demonstrating that your shape functions work properly. This is required picture 1.

    When you have a picture or scene you want to save, make a screen capture of it on a mac using the key combination Command-Shift-4. The picture will automatically be saved to a file on your Desktop. You can then move and rename it to a more appropriate location. Make sure the entire scene is visible in the image.

  3. Write functions that make more complex things

    In the shapelib.py file, make 2 functions that draw objects/things that relate to your scene. You can pick small objects, or big things. The objects should be built from several of the simpler shapes (triangles, blocks) from your library.

    When you define these aggregate shape functions, they should all take at least three parameters. The first two (x0, y0) will define the starting location for the shape and the third should define the scale of the shape. A scale factor of 1.0 should draw the shape in its natural size. Feel free to add additional parameters as you like to control other aspects of the shape. As with the basic shapes, your shapes should draw properly at any scale, location, or turtle orientation.

    For a little more detail on making aggregate shapes, see the geometric thinking page.

    In both of of your new functions, use one or more of the basic shape functions to draw the shape. For example, a house shape might incorporate the block and triangle functions. Test out your new functions before proceeding.

    In your report, include a picture demonstrating that each of your aggregate shape functions work properly. That means drawing it in several locations at several scales. This is required picture 2.

  4. Design and create a scene inspired by a Sol Lewitt artwork

    Now it is time to write the code for your scene1 function. Using the functions you created in steps 2 and 3, make a scene inspired by the Sol Lewitt work you chose. In your scene, make use of the fact that your functions can draw the shapes with different sizes in different locations. You can also use the random package and for loops to make more complex scenes, such as windows, building, trees or people at randomized locations.

    Save the image and include it in your writeup. This is required picture 3.

  5. Design and create a second scene

    Make a second, different scene in a function scene2 in your main.py file. Be creative!

    Save the image and include it in your writeup. This is required picture 4.

Follow-up Questions

  1. Does breaking a scene into pieces make it easier to create?
  2. What is a for loop and why are they useful?
  3. What is the difference between using "from turtle import *" and "import turtle"? Explain from both a practical use point of view and how they differentially affect the global symbol table.
  4. Which Sol Lewitt work did you choose as inspiration? Why?


Projects are your opportunity to learn by doing. They are also an opportunity to explore and try out new things. Rather than list out every activity for a project, the defined part of each project will be about 85% of the assignment. You are free to stop there and hand in your work. If you do all of the required tasks and do them well, you will earn a B/B+.

Extensions are your opportunity to customize your project, learn something else of interest to you, and improve your grade. The following are some suggested extensions, but you are free to choose your own. Be sure to describe any extensions you complete in your report. Include pictures.

Submit your code

Turn in your code (all files ending with .py) by putting it in a directory in the Courses server. On the Courses server, you should have access to a directory called CS151, and within that, a directory with your user name. Within this directory is a directory named Private. Files that you put into that private directory you can edit, read, and write, and the professor can edit, read, and write, but no one else. To hand in your code and other materials, copy your code into the pre-existing project directory for that week. Please submit only code that you want to be graded.

When submitting your code, double check the following.

  1. Is your name at the top of each code file?
  2. Does every function have a comment or docstring specifying what it does?
  3. Is your handin project directory inside your Private folder on Courses?

Write Your Project Report

Create a new page for your report on the wiki. Use the CS 151 template and give the page a meaningful title. Remember to put the label cs151s20project2 in the label field on the bottom of the page.

Your intended audience for your report is your peers not in the class. From week to week you can assume your audience has read your prior reports, be please minimize references to them. Your goal should be to be able to use your report to explain to friends what you accomplished in this project and to give them a sense of how you did it.

Your project report should contain the following elements. Please include a header for each section.