[R] Creating bibtex file of all installed packages?

[Achim Zeileis]

On Tue, 15 Dec 2009, Michael Friendly wrote:

> Achim and others:
>
> Achim's solution could be directly usable if it also added a BibTeX key,
> perhaps just the name of the package to the '@Manual{,' initial line of each. 
> I wrapped the previous suggestions in a function, and played around with the 
> components, but can't quite see how to account for the
> failed citation calls.  Can anyone take the next step?

I had also thought about this after sending my previous solution, so here 
is an update Michael's version of the function (renamed to the name of the 
default file). Apart from some smaller touch-ups this has the following 
changes:

   - Instead of taking the unique() bibs, I now use the unique() pkgs.

     (In principle, packages with the same name could be installed in
     different libraries, potentially containing different citations.
     But I thought it would be overkill to check for that.)

   - Citation keys are simply "pkgname" if there is only a single
     BibTeX item, and "pkgname1" to "pkgnameN" if there are N BibTeX
     items.

     (This does not assure that citation keys are unique, though. If
     there is a package "foo" with 2 citation entries and another package
     "foo2" with only a single entry, these could be confused. A workaround
     would be to use "pkgname1" instead of "pkgname" as the citation key
     even if there is a single citation only. But I thought that would
     be less intuitive.)


Rpackages.bib <- function(file = "Rpackages.bib", verbose = TRUE)
{
   ## installed packages
   pkgs <- unique(installed.packages()[,1])
   bibs <- lapply(pkgs, function(x) try(toBibtex(citation(x))))
   n.installed <- length(bibs)

   ## omit failed citation calls
   ok <- !(sapply(bibs, class) == "try-error")
   pkgs <- pkgs[ok]
   bibs <- bibs[ok]
   n.converted <- sum(ok)
   ## unify to list of Bibtex
   bibs <- lapply(bibs, function(x) if(inherits(x, "Bibtex")) list(x) else x)

   ## add bibtex keys to each entry
   pkgs <- lapply(seq_along(pkgs), function(i) if(length(bibs[[i]]) > 1)
     paste(pkgs[i], 1:length(bibs[[i]]), sep = "") else pkgs[i])
   pkgs <- do.call("c", pkgs)
   bibs <- do.call("c", bibs)
   for(i in seq_along(pkgs)) bibs[[i]][1] <-
     gsub("{,", paste("{", pkgs[i], ",", sep = ""), bibs[[i]][1], fixed = TRUE)

   ## write everything to a single .bib file
   writeLines(do.call("c", lapply(bibs, as.character)), file)
   if(verbose) cat("Converted", n.converted, "of", n.installed,
     "package citations to BibTeX",
     "\nResults written to file", file, "\n")

   ## return Bibtex items invisibly
   invisible(bibs)
}

Best,
Z