R Programming Language Certification Technology & Digital Applications 4

Question 1

Which function in the `purrr` package applies a function to each element of a list and returns a list of results?

Accepted Answer

map()

Answer

`purrr::map()` applies a function to each element of a list or vector and always returns a list, providing consistent type behavior compared to base R equivalents.

Question 2

What is the purpose of `options(scipen = 999)` in R?

Accepted Answer

Disables scientific notation for printing numbers

Answer

Setting `scipen` to a large positive value penalizes scientific notation display, causing R to print numbers in fixed-point notation instead.

Question 3

In R, which package provides the `%>%` pipe operator that passes the left-hand side as the first argument to the right-hand side function?

Accepted Answer

magrittr

Answer

The `%>%` pipe operator originates from the magrittr package, though it is re-exported by dplyr and other tidyverse packages for convenience.

Question 4

Which R function checks whether a package is installed and loads it, installing it first if necessary?

Accepted Answer

pacman::p_load()

Answer

`pacman::p_load()` checks if each listed package is installed, installs any that are missing, and then loads all of them in a single call.

Question 5

What does the `Rprof()` function do in R?

Accepted Answer

Profiles R code execution to identify performance bottlenecks

Answer

`Rprof()` activates R's built-in profiler, recording function call stacks at regular intervals so you can identify which functions consume the most execution time.

R Programming Language Certification Practice Test

R Programming Language Certification Practice Test

R Programming Language Certification Technology & Digital Applications 4