How to create dummy variables from a factor?

Question

I would like to create a set of dummy variables from a factor.

For example, the mtcars dataset has cyl values 4 , 6 , and 8 . I would like to create a set of variables such as: four_six with 4 coded as 0 and 6 coded as 1 . I eventually want to create other variables like: six_eight , four_eight .

I tried something like this using ifelse

four_six <- ifelse(cyl == 4, 0, 1)

But I would like to recode the sixes as 1 , instead of everything as 1 .

For example, I would like the eights coded as missing/NA.

Also, is there a way to programmatically do this with other functions?

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Answer 1

Just add another condition

four_six <- ifelse(cyl == 4, 0, ifelse(cyl==6, 1, NA))

or use dplyr::case_when

four_six <- dplyr::case_when(cyl==4 ~ 0, cyl==6 ~ 1)