use dplyr case_when programmatically

Question

I'm trying to use dplyr case_when and pass variable but the result was not as expected.

Example:

library(dplyr)
mtcars %>% 
  mutate(cg = case_when(carb <= 2 ~ "low",
                        carb > 2  ~ "high")) ---this works

However, when I try to pass a variable, it returns all as "low"

var <- quo(carb)
mtcars %>% 
  mutate(cg = case_when(!!var <= 2 ~ "low",
                    !!var > 2  ~ "high"))

Answer 1

This is an order of operations problem, you need to use brackets:

quo_function <- function(df, var) {
  df %>%
    mutate(cg = case_when((!!var) <= 2 ~ "low",
                          (!!var) > 2 ~ "high"))  
}

Have a look at this post this post.