R Programming Language Certification Cheat Sheet 2026

The 30 highest-yield R Programming Language Certification facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which R package provides a unified interface to train and evaluate many machine learning models? → caret
2. In R, which package and function are most commonly used to fit Support Vector Machine (SVM) models? → e1071::svm()
3. Which ggplot2 function changes the overall visual style of a plot (background, grid lines, font)? → theme()
4. Which function performs a two-sample t-test in R? → t.test()
5. What does the predict() function do when called on a fitted lm() model? → Generates predicted values for new or existing data
6. Which R function reads a CSV file into a data frame using the readr package? → read_csv()
7. In R, what does the function n() return when used inside summarise()? → The number of rows in each group
8. What argument in geom_bar() or geom_col() maps the fill color to a variable? → fill inside aes()
9. A matrix is a rectangular data collection with ____ dimensions. → 2
10. Which R package provides tools for working with strings, including pattern matching and string manipulation? → stringr
11. What role does active listening play in R Programming Language Certification practice? → It ensures accurate understanding, demonstrates respect, and improves outcomes
12. Whenever a function is called, ___ suspends execution and switches the part into debug mode. → Both of the above
13. What is reflective practice in R Programming Language Certification professional development? → Systematically examining experiences to gain insight and improve future practice
14. What R syntax should I use to output "Hello World"? → All of the other answers are correct
15. Which function computes summary statistics for each group after group_by()? → summarise()
16. How do R Programming Language Certification professionals transfer knowledge from training to practice? → Through supervised practice, mentoring, gradual independence, and ongoing feedback
17. Which dplyr function selects rows based on a condition? → filter()
18. Which function would you use to add a new computed column to a data frame in dplyr? → mutate()
19. Which of the following represents the R language's base package? → tools
20. Which tidyr function splits one column into multiple columns based on a delimiter? → separate()
21. Which ggplot2 function modifies the overall appearance of a plot (background, gridlines, fonts)? → theme()
22. What is the importance of data security in R Programming Language Certification digital applications? → Protecting sensitive information from unauthorized access, breaches, and loss is essential
23. In tidymodels, which function combines a preprocessor (recipe) and a model specification into a single object for fitting? → workflow()
24. Which of the following best justifies changing an R string (or vector of strings) from lowercase to uppercase? → It aids in data validation
25. What is the consequence of non-compliance for R Programming Language Certification professionals? → Potential fines, license revocation, legal liability, and reputational damage
26. What R classes exist for scalar data types? → numeric, character, integer, logical, complex
27. Which R package provides the map() family of functions for applying a function to each element of a list or vector? → purrr
28. What is a tibble in R? → A modern version of a data frame with better printing and stricter behavior
29. Which function adds axis labels and a title to a ggplot2 plot? → labs()
30. What does cor() compute in R? → The correlation coefficient between two or more variables