R Programming Language Certification Data Manipulation & Tidyverse in R 3

Question 1

Which R package provides tools for working with strings, including pattern matching and string manipulation?

Accepted Answer

stringr

Answer

stringi

Answer

str

Answer

textutils

Question 2

Which R function checks for missing values (NA) in a vector?

Accepted Answer

is.na()

Answer

na.check()

Answer

missing()

Answer

is.null()

Question 3

Which dplyr function removes duplicate rows from a data frame?

Accepted Answer

distinct()

Answer

unique()

Answer

deduplicate()

Answer

drop_dup()

Question 4

In R, what does the function n() return when used inside summarise()?

Accepted Answer

The number of rows in each group

Answer

The sum of a numeric column

Answer

The unique count of values

Answer

The index of the last row

Question 5

Which R package provides the map() family of functions for applying a function to each element of a list or vector?

Accepted Answer

purrr

Answer

apply

Answer

plyr

Answer

functional

Question 6

Which function from the dplyr package counts the number of rows per group?

Accepted Answer

Both count() and tally()

Answer

count()

Answer

tally()

Answer

nrow()