Making Functions in R

In this workshop you will get begin developing in R to the point that you can start crafting the tools that you need for the projects that are important to you. This workshop will cover:

• If statements and conditionals
• Three different kinds of Loops
• And creating your own functions

A basic understanding of the R programming language is recommended for this workshop.

Estimated workshop length: 2 hours

Setup Instructions

In preparation for this workshop, you will need to have a Posit account (previously was an R Studio Cloud account) and have a new R Studio project open on Posit Cloud. Follow the steps below to get set up.

• (Skip this step if you already have an Posit account) Begin by going to https://posit.cloud/ and signing up for an account by clicking on the “Sign Up” text at the top right of the screen, then click the grey “Sign Up” button and fill in the form (or use the convenient Google or GitHub options if you have one of those accounts)
• Log in to Posit
• You should arrive at your workspace. From here click on the button that says, “New Project” and select “New R Studio Project”
• Once your project has finished building, open the “Source” window by clicking on the double box symbol in the top right corner of the “Console” window

• Rename your project by clicking on the name at the top. Name it whatever you like (eg. “Making Function with R Workshop”)

• And thats it! You are all set for the workshop

Helpful Information

Conditional Statement Symbols

Format of “if” statement

if (CONDITIONAL-STATEMENT) {
    CODE-TO-EXECUTE
    } else if (CONDITIONAL-STATEMENT) {
    CODE-TO-EXECUTE
    } else {
    CODE-TO-EXECUTE
    }
  

Format of “for” loop

for (NEW-VARIABLE in VECTOR) {
    CODE-TO-EXECUTE
    }

Format of “while” loop

while (CONDITIONAL-STATEMENT) {
    CODE-TO-EXECUTE
}

Format of “repeat” loop

repeat {
    CODE-TO-EXECUTE  (REMEMBER TO INCLUDE A break() TO STOP THE LOOP)
}

Format of Timer

if (1==1){
  startTime <- Sys.time()
  
  YOUR CODE HERE
  
  endTime<- Sys.time()
  print(endTime - startTime)
}

Format for Function

FUNCTION-NAME <- function(ARGUMENT-VARIABLE-1, ARGUMENT-VARIABLE-2, …) {
return(OUTPUT-OF-FUNCTION)
}

Workshop Tasks

Task Set #1
A. Create a variable that contains a number
B. Create some code that assesses the number and returns one of the following statements:

• The number is larger than or equal to 1000
• The number is larger than or equal to 500 but less than 1000
• The number is larger than or equal to 100 but less than 500
• The number is 14
• The number is less than 100 and is not 14

C. Test out your code by redeclaring your variable with values that will get each result and then running your code again.
D. When you are done type “CODE COMPLETE!!” into the chat.

Task Set #2

A. Make a variable called numList that contains a list of 10 numbers of your choice using the c() function
B. Write a for loop that runs your code from the last set of questions on each number in the list.
C. Make a numLoops variable that has a value of 0
D. Make a numBig variable with a value over 100,000
E. Use a while loop to determine how many times you can subtract 14 from your number before it is smaller than 100
F. Make a variable called myNum with a value that is at least 6 digits long
G. Make a variable called loopGuess with a value of 0
H. Find out how long it would take for a repeat loop to go from 0 to your number
I. When you are done type “LOOPS MASTERED!!!” into the chat

Task Set #3

A. Make a variable called myList containing ten numbers between 50 and 150
B. Make a function that, when given the variable, will tell you how many of the numbers smaller than 100 and how many are equal to or greater than 100.
C. When you have finished type “GOT IT!!” in the chat
BONUS. Make it so that if there is the same amount of numbers below 100 as there are equal to or above, the result is displayed with “Perfect Balance!” at the end

Next Steps

If you are looking to continue enhancing your knowledge of R, check out our other R workshops or try out one of the options below!

YaRrr! The Pirate’s Guide to R

W3Schools R Tutorial

This workshop is brought to you by the Brock University Digital Scholarship Lab. For a listing of our upcoming workshops go to Experience BU if you are a Brock affiliate or Eventbrite page for external attendees.