Free R Programming Language: Computer Science 114 Questions and Answers

Question 1

Which one of the following creates a string in R correctly?

Accepted Answer

user <- c("Jane", "Emily", "Shauna")

Answer

In R, strings are typically enclosed in double quotes (`"`) or single quotes (`'`). To create a vector containing multiple strings, the `c()` function (combine) is used to concatenate them. Option A correctly demonstrates this syntax by creating a character vector where each string element is properly enclosed in double quotes and combined using `c()`.

Question 2

Which of the following statements most accurately sums up R's operator?

Accepted Answer

Assignment

Answer

The `<-` operator is the primary and most commonly used assignment operator in R. It is used to assign values to variables or objects. While the `=` operator can also perform assignment in many contexts, `<-` is the conventional and recommended choice in R programming for clarity and consistency.

Question 3

The starting index for R vectors is.

Accepted Answer

1

Answer

Unlike many other programming languages (e.g., Python, Java, C++) that use 0-based indexing, R vectors and other indexed data structures use 1-based indexing. This means that the first element of a vector is accessed using the index `1`, the second with `2`, and so on. This convention is important to remember when working with R data structures.

Question 4

Which of the following best justifies changing an R string (or vector of strings) from lowercase to uppercase?

Accepted Answer

It aids in data validation

Answer

Changing the case of strings (e.g., from lowercase to uppercase) in R is a common data cleaning and standardization practice. This process aids significantly in data validation by ensuring consistency across entries, preventing issues where 'apple' and 'Apple' might be treated as distinct values. Standardizing case helps in accurate comparisons, merges, and analyses, improving data quality.

Question 5

What R classes exist for scalar data types?

Accepted Answer

numeric, character, integer, logical, complex

Answer

R's fundamental scalar data types, often referred to as atomic vector types, include `numeric` (for real numbers), `character` (for text strings), `integer` (for whole numbers), `logical` (for boolean TRUE/FALSE values), and `complex` (for complex numbers). These five classes represent the basic building blocks for data storage and manipulation in R.

R Programming Language Certification Practice Test

R Programming Language Certification Practice Test

Free R Programming Language: Computer Science 114 Questions and Answers