R Programming Language Certification Data Manipulation & Tidyverse in R

Question 1

Which tidyverse package is the primary tool for data manipulation in R?

Accepted Answer

dplyr

Answer

dplyr provides a grammar of data manipulation with verbs like filter(), select(), mutate(), summarise(), and arrange().

Question 2

Which dplyr function selects a subset of rows based on a logical condition?

Accepted Answer

filter()

Answer

filter() keeps rows that satisfy one or more logical conditions, similar to WHERE in SQL.

Question 3

Which dplyr function adds new columns or transforms existing columns in a data frame?

Accepted Answer

mutate()

Answer

mutate() adds new variables or modifies existing ones while keeping all other columns in the data frame.

Question 4

What does the pipe operator |> (or %>%) do in R?

Accepted Answer

Passes the left-hand result as the first argument to the right-hand function

Answer

The pipe |> (native R 4.1+) or %>% (magrittr) passes the left-hand expression as the first argument to the right-hand function, enabling chained operations.

Question 5

Which dplyr function calculates summary statistics for groups defined by one or more variables?

Accepted Answer

summarise() after group_by()

Answer

group_by() followed by summarise() computes summary statistics (like mean, sum, count) for each group.

R Programming Language Certification Practice Test

R Programming Language Certification Practice Test

R Programming Language Certification Data Manipulation & Tidyverse in R