lab06 : Python skill builder (functions, types, if/else, strings, recursion)

num ready? description assigned due
lab06 true Python skill builder (functions, types, if/else, strings, recursion) Mon 08/21 04:00PM Fri 08/25 03:45PM

If you find typos or problems with the lab instructions, please report them on Piazza

What you’ll do in this lab

This lab is intended to be an opportunity to review, reinforce, and build your confidence with basic programming skills.

Before we move into more advanced labs and projects, we want to give you an opportunity to be sure that your understanding of the following is solid.

So, we’ve set up a series of files that contain stubs for various Python functions, along with tests for those functions.

Your job is very simple: see if you replace each of the stubs with code that passes the tests that go along with that file.

When you are finished, you can submit your solution to Gradescope for automatic “grading”. (Keep in mind that in SPIS, all so-called “grades” are just a way to get feedback on how you are doing. They don’t “count” on your permanent record in any way. Treat them as “practice” grades.)

Overview

The basic structure of the lab is similar to lab02, except for the one-time steps from that lab, and the fact that the repo you create will begin with some starter code (similar to lab04)

After creating the repo, you’ll git clone ... the repo, and then start editing Python code, trying to get test cases to pass.

Each time you get one more test case to pass, or each time you need to take a break from coding, be sure to do the git add file.py ; git commit -m "AB/CD message"; git push origin master steps.

The instructions below will give you some additional hints about each of the functions that you’ll be writing, including hints, references to help articles on the website, and/or suggestions of relevant passages in the text.

When all done, and all test cases are passing, you’ll download your project as a .zip file and submit to Gradescope for automatic checking of all your test cases.

Ok, let’s get started!

Step-by-Step Instructions

Step 1: Create your repository.

For this lab, we have made starter code available for you. Following the same procedure we had for lab04, you’ll set up the repo with Method 1, importing the starter code from this link: https://github.com/ucsd-cse-spis-2017/lab06-startercode.git

The name of your repo should be spis17-lab06-Name1-Name2, as before. And invite your pair partner to be a collaborator with admin access.

Step 2: Python coding.

In this step you will work, one file at a time, trying to replace the function stubs in each file with running code.

The process consists of:

You’ll repeat this process for each of the files pyfuncs01.py, pyfuncs02.py, etc.

For each, there some additional hints below.

pyfuncs01.py: Simple Python functions

In pyfuncs01.py, we have two simple python functions that just return a value based on their parameters.

Load the file pyfuncs01.py and the file test_pyfuncs01.py into IDLE.

You’ll need to edit and save changes to both of these files, but its the file test_pyfuncs01.py that you need to run to see if the test cases pass.

Here, you are just calculating a result by using the arithmetic operators (such as +,-,*,/,**,% etc.) and returning it.

You are also asked to add a few test cases for one of the functions in test_pyfuncs01.py.

pyfuncs02.py: Checking types

For this step, you should open the files pyfuncs02.py, and test_pyfuncs02.py.

(This pattern repeats itself for each of the remaining files pyfuncs03.py, pyfuncs04.py, and pyfuncs05.py; each one has a test file starting with test_ that goes along with it. So we won’t repeat those instructions for each step below.)

These functions return True or False based on whether their parameter is of a certain type.

You can read more about types in Python here: Python: types

You are given one example of a function that checks for type, and you are asked to write another one.

You are also asked to write some test cases for a function. Note that if you don’t write those test cases, your test_pyfuncs02.py may appear to pass even when you haven’t yet replaced the stub for one of the functions you are supposed to write.

pyfuncs03.py: boolean functions involving or

In this file, you are given a correct function definition for isAdditivePrimaryColor as an example. There is a comment that invites you to try a different way of writing the function: one that many students sometimes think will work, but that doesn’t. You are encouraged to read the comment, and experiment with that function a bit to convince yourself that the “alternative” way of writing it doesn’t work, and to try to understand why.

Then you are asked to write a correct implementation of the function isSimpleNumeric. You can use the function isAdditivePrimaryColor as an example. You may also want to consult the functions from pyfuncs02.py as a reminder of how to check for types.

As a reminder, run test_pyfuncs03.py to test the functions in this file. You actually can run these tests from the Unix command line too, by typing python test_pyfuncs03.py—you don’t actually have to open up test_pyfuncs03.py in IDLE, since you don’t have to make any changes to it.

pyfuncs04.py: first, rest, last, allButLast functions for lists and tuples

These functions are based on the idea of indexing into lists and tuples with notations such as [0], [1:], and so forth.

You may want to review the sections of Chapter 5 of your book. You are given two function definitions as examples, and then asked to replace the stubs for two more.

pyfuncs05.py: Recursion on lists and tuples

The final set of functions uses the first and rest functions to do some calculations on lists, via recursion. This is a nice opportunity to check your understanding of recursion, and practice more with the idea.

Try to understand how the totalValue function works to add up all the number in a list or tuple of numeric values. Then see if you can apply those ideas to write similar definition for productOfAll, using recursion in a similar fashion.

Next, you are asked to write two simple functions: isOdd and isEven. Those don’t involve recursion or lists; but the isOdd function is used as a helper function in two more functions in pyfuncs05.py that do involve recursion.

Once you’ve written those and gotten the test cases to pass, try to understand how the countOdds function works. Then see if you can apply those ideas to write sumOdds, using a similar recursive technique.

If you got all those tests to pass, you are pretty much done. Just a few steps to finish up and submit.

Step 7: Final check of all your tests

As one last check, run all of your tests in IDLE, or at the command line.

Here is an example of running each one of your tests at the command line. Here the bash shell prompt is replaced by simply $ to make the output easier to read. If your output looks like this, it means all of your tests are passing.

$ python test_pyfuncs01.py 
......
----------------------------------------------------------------------
Ran 6 tests in 0.000s

OK
$ python test_pyfuncs02.py 
..........
----------------------------------------------------------------------
Ran 10 tests in 0.000s

OK
$ python test_pyfuncs03.py 
........
----------------------------------------------------------------------
Ran 8 tests in 0.000s

OK
$ python test_pyfuncs04.py 
....................
----------------------------------------------------------------------
Ran 20 tests in 0.000s

OK
$ python test_pyfuncs05.py 
................................................
----------------------------------------------------------------------
Ran 48 tests in 0.001s

OK
$

That’s it for this lab!