Tidyeval equivalent of mutate_?



What is the tidyeval equivalent of mutate_(mtcars, silly = ~mpg + disp) that passes R CMD Check?


Let me test my fledgling understand of the tidyeval way to do things now:

my_var <- quo(silly)

mutate(mtcars, !!my_var := mpg + disp)


That doesn’t work:

hello <- function() {
  my_var <- quo(silly)
  mutate(mtcars, !!my_var := mpg + disp)

checking R code for possible problems … NOTE
hello: no visible binding for global variable ‘silly’
hello: no visible binding for global variable ‘mpg’
hello: no visible binding for global variable ‘disp’


I don’t know about R CMD CHECK, but Jake’s code works with my_var = "silly". We’re just looking at a variable name here, so it should not need to be evaluated.

For NSE, it looks like quo_name works:

f = function(v){
  v = quo_name(quo(v))
  mutate(mtcars, !!v := mpg + disp)


The point is that I don’t need to pass the variable names as arguments. silly, mpg and disp are hard coded names. So mutate(mtcars, silly = mpg + disp) would be sufficient but R CMD Check complains that they are global variables. The old solution was mutate_(mtcars, silly = ~ mpg + disp). I’m wondering what the tidyeval solution would be. I have the feeling the tidyeval focusses on passing variable names but I need constant names.


You need to use a pronoun:

mutate(mtcars, silly = .data$mpg + .data$disp)

And then import .data from rlang.


The tidyeval version seems great when you need to pass variable names. But it seems tedious in case of fixed variable names. I find the underscore versions easier and more readable for such cases. I hope those functions remain available.


They have been soft-deprecated and will go away in the long-term. They are convenient but the semantics are not great, and while using ~ protects you against R CMD CHECK notes, they don’t actually resolve any ambiguity.

This is nature of programming with dplyr and similar - you lose a lot of the advantages in favour of informative error messages.


I think the better long term plan is to enable R to know about quoting functions. R CMD check should not analyse the calls of such functions. In the meantime if you’re writing a package and don’t want to use the .data pronoun it’s easy to maintain a list of global variables with utils::globalVariables(), even though it feels like you shouldn’t need to.