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Top 25 R Interview Questions and Answers

11/Sep/2021 | 8 minutes to read


Here is a List of essential R Interview Questions and Answers for Freshers and mid level of Experienced Professionals. All answers for these R questions are explained in a simple and easiest way. These basic, advanced and latest R questions will help you to clear your next Job interview.

R Interview Questions

R Interview Questions and Answers

These interview questions are targeted for R Programming Language or R for Data Science. You must know the answers of these frequently asked R interview questions to clear the interview. A Data Scientist or Machine Learning Engineer should know the answers of these R interview questions.

1. Explain R programming language. What is the R environment?

R - a GNU Project, is a Programming language and environment software for statistical computing (classical statistical tests, linear and nonlinear modelling, classification, time-series analysis, clustering etc.) and graphics. R is a highly extensible language which provides various statistical and graphical techniques.
R Environment is an integrated suite which facilitates data calculation, data manipulation and graphical display of data. R environment includes:

  • Handles data effectively and provides a data storage facility.
  • A set of operators to perform operations on arrays, in specific matrices.
  • Large, integrated and coherent set of tools for Data analysis.
  • Graphical techniques for displaying data (on screen or on hard copy) and data analysis.
  • A Programming language which can perform all operations such as loop, conditional, input, output and recursive functions etc.
For more visit R Project.

2. Differentiate R vs Python.

3. What are Global variables in R?

4. Explain Recursive function with an example in R.

5. How to return multiple values in R?

6. What are infix operators in R? How do they work?

7. Explain different data structures in R.

8. What is the difference between Matrix and Data frame?

9. What is the data frame in R?

10. How to check if a variable is a data frame or not?

11. Explain DataFrame Operations in R.

12. What are the factors in R?

13. What are three class systems in R?

14. What is S3 class in R?

15. What is S4 class in R?

16. What is a Reference class in R?

17. Explain Inheritance in R?

18. Differentiate S3 vs S4 vs Reference class.

19. What is an Object?

Code example 1 - For below code, you have a data.frame
df <- data.frame(a=c(1, 2, 3), b=c(4, 5, 6), c(7, 8, 9))

20. How to select the c(4, 5, 6) in code example 1?

21. How to select the 1 in code example 1?

22. How to select the 5 in code example 1?

23. What is the value of df[, 3] in code example 1?

24. What is the value of df[1,] in code example 1?

25. What is the value of df[2, 2] in code example 1?

Some General Interview Questions for R

1. How much will you rate yourself in R?

When you attend an interview, Interviewer may ask you to rate yourself in a specific Technology like R, So It's depend on your knowledge and work experience in R.

2. What challenges did you face while working on R?

This question may be specific to your technology and completely depends on your past work experience. So you need to just explain the challenges you faced related to R in your Project.

3. What was your role in the last Project related to R?

It's based on your role and responsibilities assigned to you and what functionality you implemented using R in your project. This question is generally asked in every interview.

4. How much experience do you have in R?

Here you can tell about your overall work experience on R.

5. Have you done any R Certification or Training?

It depends on the candidate whether you have done any R training or certification. Certifications or training are not essential but good to have.


We have covered some frequently asked R Interview Questions and Answers to help you for your Interview. All these Essential R Interview Questions are targeted for mid level of experienced Professionals and freshers.
While attending any R Interview if you face any difficulty to answer any question please write to us at Our IT Expert team will find the best answer and will update on the portal. In case we find any new R questions, we will update the same here.