CSC121: Exercise 3

Due: Thursday, February 8th by 11:00pm

IMPORTANT NOTE: Make sure your e3.R does not have any errors when you 'source' it.
Starting with E3, if any errors occur when sourcing the file, you will get zero.

What to hand in

Submit one file, which must be named "e3.R" (without the quotation marks). Exercises are to be done individually.

Check that file name!

Once you have submitted on MarkUs, be sure to check that you have submitted the correct versions; new or missing files will not be accepted after the due date. Spelling of filenames, including case, counts. If your file is not named exactly as required, your mark will be zero.

If you realize you have submitted an incorrectly named file, just fix the name and resubmit. There is no need to get rid of the wrongly-named file.

Watch that clock!

We will mark the newest version submitted not later than the deadline. Don't submit just once; instead, submit at least once well in advance, so that you know what you're doing, and then keep submitting new versions as you do more of the exercise. That way, if you run out of time on the last function that you just can't do, you'll still get marks for the others.

What to put in e3.R

Download e3_starter.R and rename it to e3.R. In this file, we have provided both the function header and the docstring for all the functions that you need to have in the file e3.R.

You need to write the function body for each of these four functions. Simply add your code below each comment that says # Add your code here. You need to write these functions using proper R structure and style. Although we are not marking your style, it is important to have a look at at the R Style Guidelines and use them so that you create good habits. Use intermediate variables to help describe what your function is doing. Do not put your whole function into the return statement.

Example Test Cases

Here are some examples of test cases in the R Console with the correct expected value for the functions: Test Cases

Important Instructions!

Remember, you are only submitting the function definitions. You do not need to submit any test cases or R Console output.

Like the name of the file itself, the names of the functions must be spelled exactly as shown. You should not change them.

Do not call print or cat in your functions, and do not write any code outside of the function definitions. Doing so may cause your code to fail the tests.

How to check your code

You will make mistakes! Be sure to check your functions by sourcing them in RStudio, and creating a separate R script for testing your function. Make some test cases (like we did in class and lab), and make sure your function works with different arguments. Ensure you get back what you expect when you call your functions. Do not just check the example test cases, but test the functions with test cases of your own too.

If you need help

Please make use of any of the resources listed here: Getting Help

Autotesting

We will be autotesting your code for correctness after the submission deadline. An announcement will be made once autotesting results are available, likely a week after the submission deadline, as there may be some delays while we get everything set up.