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ECS 189G, Spring 2023, Quiz 0

This is Quiz 0. It will be different from the other quizzes, which will be in-class (weekly in the disucssion section, and also in lecture on the last day of class).

This particular quiz is meant to be extremely easy. Its main purposes are (a) to acquaint you with using OMSI and (b) to make sure you have basic skills in R.

Make SURE to read the instructions carefully.

Instructions

  • You must use the OMSI tool to submit your quiz. Make SURE to do a test run first, playing the role of both the student and instructor, as explained in the OMSI docs.

  • This will be due 11:59 pm, April 13. The TA will start the OMSI server on April 6 (machine and port to be announced). You may submit at any time between April 6 and 11. Don't leave it for the last minute; keep in mind my slogan, "Computers never work." :-)

  • You should be able to get an A+ grade on this quiz! You are welcome to seek help from me or our TA (you may ask more than once if needed):

    You are not allowed to discuss this quiz with anyone else besides me and the TA. Failure to adhere to this requirement will be considered a violation of the Code of Academic Conduct.

  • Prepare for this quiz by learning the rudiments of R, in my fasteR tutorial. For now, the first dozen lessons or so will probably suffice, but as the quarter progresses, continue reading.

  • Quiz questions, both here and in future quizzes, will be labeled either "R code answer" or "Text answer." In the former case:

    • The OMSI grading tool will execute exactly what you submit. Accordingly, there should be NO non-R in your submission.

    • If the question asks for you to just write a function, that is all you must have in your submission. If you would like to include test code, do so and run to check but comment it out before submitting.

    • Use R comment lines to show your work and explain your answer, in order to better attain partial credit if you are wrong.

    • A question may ask you to "print" something. This means, "print to the screen," i.e. use the print() function or equivalent.

    • When a question asks you to write code, it means it. Don't compute something by hand and then merely submit the number.

    • You are not required to include error-checking unless specifically asked to do so.

    • One question here will use the german.credit dataset from the fairml package. In addition to here in Quiz 0, make sure you have this package on your laptop for future quizzes.

The quiz questions

Question 1: Consider the mtcars dataset, built-in to R. Write code that finds and prints the hp value in the third row of the dataset.

Question 2: Again with the mtcars dataset, write code that finds and prints the mean mpg among cars having 6 or 8 cyclinders.

Question 3: Again with the mtcars dataset, write code that adds a new column, the horsepower/weight ratio, and prints the entire new dataset, now 12 columns rather than 11.

Question 4: In the german.credit data, write code that prints: the proportion of foreign workers who have good credit; the proportion of workers with good credit who are foreign; the proportion of foreign workers; and the proportion of workers who have good credit. (Print a 4-element vector.)