STT 180 Exam 1 Questions and Correct Answers

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STT 180 Exam 1 Questions and Correct
Answers
Is a dplyr function that chooses rows matching a set of criteria
Ans: filter()




ex. flights %>%

filter(air_time > 60)

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




ex. slice(mtcars, 1:3)

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




ex. mtcars %>%

select(mpg, hp, wt)

Grabs a column as a vector Ans: pull()




ex. mtcars %>%

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pull(1) or pull(cyl)

rename specific columns Ans: rename()




ex. mtcars %>%

rename(NewName = OldName)

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




ex. mtcars %>%

arrange(cyl) ##Ascending

arrange(cyl,mpg) ##Reorders both

arrange(desc(cyl)) ##Descending

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




ex. mtcars %>%

mutate(new_variable = mpg/5)

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




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