Where can I find documentation on the `..*..` ggplot options?

Question

I use ..density.. from time to time, and it's great. There's lots of examples of it in the ggplot2 book, as well as ..count... Looking through the stat_density documentation, I learned about ..scaled... Seeing someone use ..n.. here on StackOverflow, I found out about that. Now I just wonder what else I'm missing.

Search engines seem to ignore the .s in search strings like "..n.. ggplot2", even if I escape them. Is there a general term for these variables? Are there more? Where can I find documentation on them?

Answer 1

Here are all of the ..*.. options mentioned in the ggplot2 help files (or at least those help files that can be brought up by typing ?"<func>", where "<func>" refers to one of the functions exported by ggplot2).

library(ggplot2)

## Read all of the ggplot2 help files and convert them to character vectors
ex <- unlist(lapply(ls("package:ggplot2"), function(g) {
    p = utils:::index.search(g, find.package(), TRUE)
    capture.output(tools::Rd2txt(utils:::.getHelpFile(p)))
}))

## Extract all mentions of "..*.." from the character vectors
pat <- "\\.\\.\\w*\\.\\."
m <- gregexpr(pat, ex)    
unique(unlist(regmatches(ex,m)))
# [1] "..density.."  "..count.."    "..level.."    "..scaled.."   "..quantile.."
# [6] "..n.."   

Or, to find out which help files document which ..*.., run this:

library(ggplot2)

ex <- sapply(ls("package:ggplot2"), function(g) {
    p = utils:::index.search(g, find.package(), TRUE)
    capture.output(tools::Rd2txt(utils:::.getHelpFile(p)))
}, simplify=FALSE, USE.NAMES=TRUE)

res <- lapply(ex, function(X) {
    m <- gregexpr("\\.\\.\\w*\\.\\.", X)    
    unique(unlist(regmatches(X, m)))
})
res[sapply(res, length) > 0]