I'd like to write a function that takes a quosure as an argument, appends - to the quosure, and passes that to gather, like so:
library(tidyverse)
my_gather <- function(d, not.columns) {
dg <- tidyr::gather(d, key = k, value = v, .dots = -!!!not.columns)
dg
}
de <- my_gather(mtcars, not.columns = quos(mpg, cyl, disp))
> Error in `-`(~mpg, ~cyl, ~disp) : operator needs one or two arguments
This is clearly because I need to append each element of the quosure with -, rather than appending the entire quosure with -. But in my work, it won't be easy to create this quosure in the form of quos(-mpg, -cyl, -disp) - so how can I modify quos(mpg, cyl, disp) to add the -?
I would like to see a result that is identical to gather(mtcars, key = k, value = v, -mpg, -cyl, -disp), the first 3 rows of which are
mpg cyl disp k v
1 21.0 6 160 hp 110
2 21.0 6 160 hp 110
3 22.8 4 108 hp 93
There's a similar question here, but it is unanswered and doesn't seem to deal with the issue of quos() rather than quo().
We can do
my_gather <- function(d, not.columns) {
tidyr::gather(d, key = k, value = v, .dots = -c(UQS(not.columns)))
#or use !!! instead of UQS
#tidyr::gather(d, key = k, value = v, .dots = -c(!!!(not.columns)))
}
de <- my_gather(mtcars, not.columns = quos(mpg, cyl, disp))
head(de, 3)
# mpg cyl disp k v
#1 21.0 6 160 hp 110
#2 21.0 6 160 hp 110
#3 22.8 4 108 hp 93
Checking with the output without the function
de1 <- gather(mtcars, key = k, value = v, -mpg, -cyl, -disp)
identical(de, de1)
#[1] TRUE