STT 180 Exam 1 Questions with Answers (100% Correct Answers)

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STT 180 Exam 1 Questions with Answers (100% Correct
Answers)

Is a dplyr function that chooses rows matching a set of criteria

Answer: filter()




ex. flights %>%

filter(air_time > 60)

Is a dplyr function that chooses rows using indices Answer: slice()




ex. slice(mtcars, 1:3)

Is a function of dplyr that chooses columns by name Answer: select()




ex. mtcars %>%

select(mpg, hp, wt)

Grabs a column as a vector Answer: pull()

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ex. mtcars %>%

pull(1) or pull(cyl)

rename specific columns Answer: rename()




ex. mtcars %>%

rename(NewName = OldName)

reorder rows in ascending and descending order Answer: arrange()




ex. mtcars %>%

arrange(cyl) ##Ascending

arrange(cyl,mpg) ##Reorders both

arrange(desc(cyl)) ##Descending

adds new variables to the data frame Answer: mutate()



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ex. mtcars %>%

mutate(new_variable = mpg/5)

creates a new data frame with new variables Answer: transmute()




ex. mtcars%>%

transmute(new_var = mpg/5)

filters for unique rows (so it gets rid of duplicates) Answer: distinct()




ex. distinct(df, x) so distinct(mtcars, mpg)




or




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