R Programming Language Certification Data Manipulation & Transformation 2

Question 1

Which tidyr function separates a single column into multiple columns based on a delimiter?

Accepted Answer

separate()

Answer

unite()

Answer

extract()

Answer

split_col()

Question 2

Which dplyr function removes duplicate rows from a data frame?

Accepted Answer

distinct()

Answer

unique_rows()

Answer

dedupe()

Answer

filter_unique()

Question 3

What is the result of left_join(df1, df2, by='id') in dplyr?

Accepted Answer

All rows from df1, matched rows from df2

Answer

Only rows in df2

Answer

Only matching rows from both

Answer

All rows from both data frames

Question 4

Which function in base R applies a function to each element of a list and returns a list?

Accepted Answer

lapply()

Answer

sapply()

Answer

vapply()

Answer

tapply()

Question 5

In dplyr, which function is used to reorder rows based on column values?

Accepted Answer

arrange()

Answer

sort()

Answer

order()

Answer

rank()

Question 6

Which function replaces NA values with a specified value in R?

Accepted Answer

replace_na()

Answer

fill_na()

Answer

impute()

Answer

coalesce_na()