Using string as variable on LHS and in mutate command

Question

I have the following function which works fine, but I am not sure if this is the actual way to do it as programming with tidyverse changed over the last year(s). I am especially interested in using a more consistent way of using strings on the LHS and RHS. In my example, there are three ways at the moment: !!, {{}} and !!as.name().

noga_data <- tibble(NOGA = c("01", "02", "03", "05"))

assign_noga_class <- function(mydata, noga2, noga_class) {

  mydata %>% 
    mutate(!!noga_class := ifelse(as.numeric({{ noga2 }} ) %in% c(1:3), 1, NA)) %>% 
    mutate(!!noga_class := ifelse(as.numeric({{ noga2 }}) %in% c(5:34), 2, !!as.name(noga_class)))
}
assign_noga_class(noga_data, NOGA, "NOGA_CLASS")

I thought that the bang-bang notation was outdated/superseded by something else. I like to know because I am using this as an example for a group I would like to teach about programming in R. Any hints on blogs or other web pages are also very welcome.

Cheers

Renger

Answer 1

I don’t think !! is deprecated, but you can now use glue syntax to interpolate variable names (docs):

library(dplyr)

assign_noga_class <- function(mydata, noga2, noga_class) {
  mydata %>% 
    mutate("{noga_class}" := ifelse(as.numeric({{ noga2 }} ) %in% c(1:3), 1, NA)) %>% 
    mutate("{noga_class}" := ifelse(as.numeric({{ noga2 }}) %in% c(5:34), 2, !!as.name(noga_class)))
}

assign_noga_class(noga_data, NOGA, "NOGA_CLASS")

# A tibble: 4 × 2
  NOGA  NOGA_CLASS
  <chr>      <dbl>
1 01             1
2 02             1
3 03             1
4 05             2

This can be handy if you want to add to the passed variable name, e.g.,

assign_noga_class <- function(mydata, noga2, noga_class) {
  mydata %>% 
    mutate("{noga_class}" := ifelse(as.numeric({{ noga2 }} ) %in% c(1:3), 1, NA)) %>% 
    mutate("{noga_class}_v2" := ifelse(as.numeric({{ noga2 }}) %in% c(5:34), 2, !!as.name(noga_class)))
}

assign_noga_class(noga_data, NOGA, "NOGA_CLASS")

# A tibble: 4 × 3
  NOGA  NOGA_CLASS NOGA_CLASS_v2
  <chr>      <dbl>         <dbl>
1 01             1             1
2 02             1             1
3 03             1             1
4 05            NA             2

Finally, as @Jean-ClaudeArbaut points out, you can also use {{: e.g., mutate({{noga_class}} := ifelse(....