Function definition in R Programming - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a function in R?

A function in R is a block of code designed to perform a specific task. It can take inputs, called arguments, and return an output.

beginner

How do you define a simple function in R that adds two numbers?

You use the syntax: <br>

add <- function(x, y) {
  return(x + y)
}

<br>This creates a function named 'add' that returns the sum of x and y.

beginner

What does the 'return()' statement do inside an R function?

The 'return()' statement sends the result back to where the function was called. It ends the function and outputs the value inside return().

beginner

Can an R function have no arguments? Give an example.

Yes, an R function can have no arguments. Example:<br>

hello <- function() {
  print("Hello, world!")
}

<br>This function prints a greeting when called.

beginner

How do you call a function named 'multiply' with arguments 3 and 4 in R?

You call it by writing:<br>

multiply(3, 4)

<br>This runs the function with 3 and 4 as inputs.

What keyword is used to define a function in R?

A function

B def

C func

D fun

In R, the keyword 'function' is used to define a function.

What does the following R code do?<br>

f <- function(x) { x * 2 }

A Prints x times 2

B Calls a function named f

C Creates a variable x with value 2

D Defines a function that doubles x

The code defines a function 'f' that takes input x and returns x multiplied by 2.

How do you return a value from a function in R?

A Using return()

B Using output()

C Using print()

D Using send()

The 'return()' function sends a value back from the function.

Which of these is a valid function call in R?

A myfunc 5, 10

B myfunc(5, 10)

C call myfunc(5, 10)

D myfunc->(5,10)

Functions in R are called by writing the function name followed by parentheses with arguments inside.

Can an R function have no arguments?

A Only if it returns NULL

B No

C Yes

D Only if it is anonymous

Functions in R can be defined without any arguments.

Explain how to define and call a function in R that takes two numbers and returns their sum.

Think about the syntax: name <- function(args) { ... } and how to use return()

Describe what happens when you call a function in R and how the return value is used.

Imagine the function as a machine that takes input and gives output.