aes_string had some convenient behaviours that I made use of when programming with ggplot2. But aes_string has been deprecated (noticeably since ggplot2 version 3.4.0 I believe). I am struggling with how to nicely replace it.
Specifically, I previously created functions that accepted arbitrary string arguments through the ellipsis, and passed these to aes_string via do.call, as shown in the first reprex below.
Since noticing the deprecation warning I have tried to avoid aes_string, and found myself effectively just mimicking it in a rather "hacky" looking way.
Presumably, whatever flaw in aes_string led to its deprecation, would also apply to my hacky workaround. See the second reprex.
Is there a more elegant solution? I want to continue passing the variable names as strings.
Reprex of my old approach with aes_string
library(ggplot2)
plotterOld <- function(...) {
args <- list(...)
pointAes <- do.call(aes_string, args = args)
ggplot(mpg, aes(displ, cty))
geom_point(mapping = pointAes)
}
plotterOld(colour = "cyl", size = "year")
#> Warning: `aes_string()` was deprecated in ggplot2 3.0.0.
#> ℹ Please use tidy evaluation ideoms with `aes()`
# it can accept NULLs, and e.g. intuitively doesn't map size to anything
plotterOld(colour = "cyl", size = NULL)
# no arguments also works fine
plotterOld()
Created on 2022-11-11 with reprex v2.0.2
Reprex of my hacky attempt at replacing aes_string's behaviour?
library(ggplot2)
# arbitrary aesthetics passed as strings using ellipses, aes, quo and .data
myAesString <- function(...) {
dots <- list(...)
# early exits
stopifnot(rlang::is_named2(dots))
if (length(dots) == 0) {
return(NULL)
}
# initialise empty mapping object and fill it with quosures where appropriate
mapping <- aes()
for (n in names(dots)) {
v <- dots[[n]]
if (!is.null(v)) {
if (!rlang::is_string(v)) stop(n, " must be a string or NULL")
mapping[[n]] <- quo(.data[[v]])
}
}
return(mapping)
}
plotterNew <- function(...) {
pointAes <- myAesString(...)
ggplot(mpg, aes(displ, cty))
geom_point(mapping = pointAes)
}
plotterNew(colour = "cyl", size = "year")
plotterNew(colour = "cyl", size = NULL, shape = "drv")
plotterNew()
# seems to work fine
p <- plotterNew(colour = "cyl", size = "year")
p$layers[[1]]$mapping
#> Aesthetic mapping:
#> * `colour` -> `.data[["cyl"]]`
#> * `size` -> `.data[["year"]]`
Created on 2022-11-11 with reprex v2.0.2
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CodePudding user response：
One option would be to convert your list of quoted strings to symbols using sym:
library(ggplot2)
plotterOld <- function(...) {
args <- lapply(list(...), function(x) if (!is.null(x)) sym(x))
pointAes <- do.call(aes, args = args)
ggplot(mpg, aes(displ, cty))
geom_point(mapping = pointAes)
}
UPDATE And we could simplify even further by using !!! to get rid of do.call:
plotterOld <- function(...) {
args <- lapply(list(...), function(x) if (!is.null(x)) sym(x))
ggplot(mpg, aes(displ, cty))
geom_point(mapping = aes(!!!args))
}
plotterOld(colour = "cyl", size = "year")
plotterOld(colour = "cyl", size = NULL)
plotterOld()
CodePudding user response：
You can use ensyms to convert named string arguments to named symbol arguments, so the equivalent to your old plotting function could be
library(ggplot2)
plotterNew <- function(...) {
ggplot(mpg, aes(displ, cty))
geom_point(mapping = aes(!!!ensyms(...)))
}
plotterNew(colour = "cyl", size = "year")
Created on 2022-11-12 with reprex v2.0.2