R Programming Language Certification Data Manipulation & Tidyverse in R 2

Question 1

Which tidyr function converts data from wide format to long format?

Accepted Answer

pivot_longer()

Answer

gather()

Answer

melt()

Answer

reshape()

Question 2

Which dplyr join function keeps all rows from the left data frame and matching rows from the right?

Accepted Answer

left_join()

Answer

inner_join()

Answer

full_join()

Answer

semi_join()

Question 3

Which R function reads a CSV file into a data frame using the readr package?

Accepted Answer

read_csv()

Answer

read.csv()

Answer

fread()

Answer

import_csv()

Question 4

What is a tibble in R?

Accepted Answer

A modern version of a data frame with better printing and stricter behavior

Answer

A list of vectors

Answer

A matrix with labels

Answer

A tidyverse plot object

Question 5

Which dplyr function selects specific columns from a data frame by name or condition?

Accepted Answer

select()

Answer

filter()

Answer

pull()

Answer

keep()

Question 6

Which tidyr function splits one column into multiple columns based on a delimiter?

Accepted Answer

separate()

Answer

split_col()

Answer

str_split_col()

Answer

divide()