Help with a function

tidyverse
1

Hello. I am a relative newcomer to R and I'm having some difficulty with what I thought would be a fairly simple function. Here is a sample:

Recode01 <- function(data, varname) {
  varname = enquo(varname)
  data <- data %>%
    mutate((!!varname) :=
        case_when((!!varname) == 1 ~ 4,
                  (!!varname) == 2 ~ 3,
                  (!!varname) == 3 ~ 1,
                  (!!varname) == 4 ~ 0,
                  (!!varname) == 5 ~ 2))
  
}

col1 <- c(1:5)
df1 <- as.data.frame(col1)
Recode01(df1, col1)

When I submit this literally nothing happens. Please note that when submitted as straight code it works as intended. See:

df1 <- df1 %>% 
    mutate(col1 =
        case_when(col1 == 1 ~ 4,
                  col1 == 2 ~ 3,
                  col1 == 3 ~ 1,
                  col1 == 4 ~ 0,
                  col1 == 5 ~ 2))

Thank you in advance.

2

You need to return() the value of data or not assign the result of the mutate() to data so that the result is returned by the function.

library(tidyverse)
Recode01 <- function(data, varname) {
  varname = enquo(varname)
  data <- data %>%
    mutate((!!varname) :=
             case_when((!!varname) == 1 ~ 4,
                       (!!varname) == 2 ~ 3,
                       (!!varname) == 3 ~ 1,
                       (!!varname) == 4 ~ 0,
                       (!!varname) == 5 ~ 2))
  return(data)
  
}

col1 <- c(1:5)
df1 <- as.data.frame(col1)
Recode01(df1, col1)
#>   col1
#> 1    4
#> 2    3
#> 3    1
#> 4    0
#> 5    2

Recode02 <- function(data, varname) {
  varname = enquo(varname)
  data %>%
    mutate((!!varname) :=
             case_when((!!varname) == 1 ~ 4,
                       (!!varname) == 2 ~ 3,
                       (!!varname) == 3 ~ 1,
                       (!!varname) == 4 ~ 0,
                       (!!varname) == 5 ~ 2))
  
}
Recode02(df1, col1)
#>   col1
#> 1    4
#> 2    3
#> 3    1
#> 4    0
#> 5    2

Created on 2024-03-02 with reprex v2.0.2

3

Duh! Thank you. I had tried return(!!varname) but that didn't do it. Again, thanks. I do like this language after many years of SAS coding.