R Programming - Functions MCQ Questions and Answers

Functions in R are fundamental building blocks that help you execute reusable blocks of code. R provides a wide variety of built-in functions, and you can also create your own custom functions to perform specific tasks. Understanding how to use and define functions is crucial for efficient programming.

This quiz will test your knowledge of R functions, including how they are defined, called, and utilized in different scenarios. Each question is accompanied by an explanation to help clarify the concept.

Let’s begin with these multiple-choice questions (MCQs) to enhance your understanding of R functions.

1. How do you define a function in R?

a) function_name <- function()

b) function function_name()

c) def function_name()

d) func function_name()

Answer:

a) function_name <- function()

Explanation:

In R, a function is defined using the syntax function_name <- function(), where function() contains the function logic.

2. How do you call a function in R?

a) call function_name()

b) function_name()

c) run function_name()

d) execute function_name()

Answer:

b) function_name()

Explanation:

To call a function in R, you simply use the syntax function_name().

3. Which function in R returns the number of rows in a data frame?

a) ncol()

b) length()

c) nrow()

d) count()

Answer:

c) nrow()

Explanation:

The nrow() function returns the number of rows in a data frame or matrix.

4. What does the return() function do in R?

a) Ends a function and returns a value

b) Prints a message

c) Stops a script

d) None of the above

Answer:

a) Ends a function and returns a value

Explanation:

The return() function in R is used to return a value from a function and end its execution.

5. What is the output of mean(c(2, 4, 6))?

a) 4

b) 6

c) 2

d) 5

Answer:

a) 4

Explanation:

The mean() function calculates the average of a numeric vector. The mean of c(2, 4, 6) is 4.

6. How do you define a function with a default argument in R?

a) function_name <- function(x = 5)

b) function_name <- function(x <- 5)

c) function_name <- def(x = 5)

d) func function_name(x = 5)

Answer:

a) function_name <- function(x = 5)

Explanation:

In R, a default argument is set using the syntax function_name <- function(x = 5), where x takes the value 5 if not provided during the function call.

7. What does the sum() function do in R?

a) Finds the average of numbers

b) Finds the sum of numbers

c) Finds the difference between numbers

d) None of the above

Answer:

b) Finds the sum of numbers

Explanation:

The sum() function in R returns the total sum of all the elements in a vector.

8. How can you pass multiple arguments to a function in R?

a) Using a list

b) Using the c() function

c) Passing them as individual parameters

d) Using a matrix

Answer:

c) Passing them as individual parameters

Explanation:

Multiple arguments are passed to a function by specifying them individually, separated by commas, in the function call.

9. What does the rep() function do in R?

a) Repeats a value or vector

b) Returns the average of a vector

c) Removes duplicates from a vector

d) Returns the reverse of a vector

Answer:

a) Repeats a value or vector

Explanation:

The rep() function repeats a value or a vector a specified number of times in R.

10. What is the purpose of the str() function in R?

a) Converts a value to a string

b) Extracts a substring

c) Displays the internal structure of an object

d) Joins two strings together

Answer:

c) Displays the internal structure of an object

Explanation:

The str() function in R displays the internal structure of an R object, which is useful for data inspection.

11. Which of the following functions returns the maximum value in a vector?

a) min()

b) max()

c) range()

d) summary()

Answer:

b) max()

Explanation:

The max() function returns the largest value from a given vector.

12. What does the apply() function do in R?

a) Applies a function over rows or columns of an array or matrix

b) Removes missing values from a vector

c) Sorts a vector

d) Combines two vectors

Answer:

a) Applies a function over rows or columns of an array or matrix

Explanation:

The apply() function applies a specified function to the rows or columns of a matrix or array in R.

13. Which function in R combines multiple vectors into a data frame?

a) rbind()

b) merge()

c) data.frame()

d) cbind()

Answer:

c) data.frame()

Explanation:

The data.frame() function is used to combine multiple vectors into a data frame in R.

14. What does the lapply() function do in R?

a) Applies a function to each element of a list and returns a list

b) Applies a function to a matrix

c) Sorts a list

d) None of the above

Answer:

a) Applies a function to each element of a list and returns a list

Explanation:

The lapply() function in R applies a specified function to each element of a list and returns the result as a list.

15. How do you remove NA values from a vector in R?

a) remove_na()

b) rm.na()

c) na.omit()

d) delete_na()

Answer:

c) na.omit()

Explanation:

The na.omit() function removes NA values from a vector or data set in R.

These questions provide insights into the use and definition of functions in R. Mastering functions allows you to write reusable code and handle complex operations more efficiently. Keep practicing to strengthen your understanding of R functions.