How to use or (" | ") in ifelse in r programming for categorial value

Question

For example, I want to make a subcategory from column data1 to data2. It will categorize if A or B, and it will put a value of 1 for it, else 0.

Project_R2 $data2 = ifelse (Project_R2 $data1 =="A" | "B", 1,0). 

This code is not working for me.

Answer 1

There are more options, so you can try this:

Project_R2$data2 = ifelse(Project_R2$data1 =="A" | Project_R2$data1 == "B", 1,0)

And as @markus mentioned in the comments, you can also use this:

Project_R2$data2 = ifelse(Project_R2$data1 %in% c("A", "B"), 1,0)

Answer 2

With %in% you can test if elements are part of a set which makes it equivalent to | (as recommended by @Markus). It gives the same result

Project_R2 <- data.frame(data1 = c("A", "C", "B", "D", "B", "A", "C", "D"))

Project_R2$data2 = ifelse(Project_R2$data1 %in% c("A", "B"), 1, 0)
Project_R2$data2
#> [1] 1 0 1 0 1 1 0 0

Or even shorter but a bit less obvious to understand (as.integer coerces TRUE to 1 and FALSE to `0``)

Project_R2$data2 = as.integer(Project_R2$data1 %in% c("A", "B"))
Project_R2$data2
#> [1] 1 0 1 0 1 1 0 0

^{Created on 2022-04-15 by the reprex package (v2.0.1)}