Lecture 01b Practice

These activities are for practice only — there is nothing to turn in. Answer keys are included, so try each question yourself before opening them.

Question 1 (R and RStudio)

There are many ways to customize the RStudio interface. To explore the possibilities, go to Tools > Global Options. The most noticeable things you can change are aspects of RStudio’s appearance. If you click on the Appearance section, you can select a different zoom level, editor font, font size, and editor theme. I usually teach with the default settings and you can keep everything the same if you want your computer to match the one I teach from, but for my own work I use the “Tomorrow Night 80s” theme and a custom font called Fira Code. I also make slight changes to the Pane Layout section that I’d be happy to describe to you in class if you’re interested.

All of this stuff is optional, but a few changes that I’d recommend making are to go to the General section and make sure that “Restore .RData into workspace at startup” is unchecked and that “Save workspace to .RData on exit” is set to “Never”. Finally, under the Code section and the Display tab, I like to check the box for “Allow scroll past end of document”.

Question 2 (Console)

Read what the user wanted to do and look at the command they sent to R. Fix the errors in the commands and calculate the answers.

  1. I want to add 20 and 0.2 and divide that sum by 4.1. But I get an error when I try:
    [20 + .2] \ 4.1
  2. I want to multiply 6 by the sum of 2 and 1,300. But I get an error when I try:
    6 x (2 + 1,300)

Click here for the answer key

Answer (a)

Change the brackets [] to parentheses () because parentheses () are the order-of-operations operator in R. Also, change the backslash \ to a forward slash / because forward slash / is the division operator in R.

(20 + .2) / 4.1
#> [1] 4.926829

Answer (b)

Change the x to an asterisk * because asterisk * is the multiplication operator in R. Also, remove the comma , from 1,300 because R doesn’t use commas to delimit digits in large numbers.

6 * (2 + 1300)
#> [1] 7812

Question 3 (Scripts)

Create a new R script file and copy your answers to Question 2 into it. Add some comments to explain which line of code corresponds to 2a and 2b. It is a good idea to get into the practice of keeping your code organized and commented. Organized code will also make grading easier, and a happy grader is associated with a happy student. 😉

Click here for the answer key 
#### File > New File > R Script (or equivalent shortcuts)

# Question 2a
(20 + .2) / 4.1

# Question 2b
6 * (2 + 1300)

#### File > Save (or equivalent shortcuts)

Fun Stuff: The Literal Genie

What it feels like to talk to R sometimes…