R Programming Language Certification R Programming Language: Computer Science 2

Question 1

Which R function returns the number of elements in a vector?

Accepted Answer

length()

Answer

length() returns the total number of elements in a vector or list.

Question 2

What does the '%%' operator do in R?

Accepted Answer

Modulo (remainder)

Answer

The %% operator returns the remainder after division, e.g., 7 %% 3 returns 1.

Question 3

In R, which class does the result of `1L` belong to?

Accepted Answer

integer

Answer

The L suffix forces R to store the value as an integer rather than a double.

Question 4

What is the output of `which(c(FALSE, TRUE, FALSE, TRUE))`?

Accepted Answer

c(2, 4)

Answer

which() returns the indices of TRUE values; positions 2 and 4 are TRUE.

Question 5

Which statement correctly creates a named list in R?

Accepted Answer

list(name='Alice', age=30)

Answer

list() with named arguments creates a named list; c() creates a named vector but coerces types.

R Programming Language Certification Practice Test