Accessing “examples” subdirectory in R-package

Question

I using a CRAN package which contains a subdirectory "examples/" containing a file "ex.txt". How do I access this file?

I tried

require("XX")
read.table(paste(.path.package("XX"), "/examples/ex.txt", sep=""), header=TRUE, sep="\t")

but then the file is not found. When I look in the installation directory of the package, I indeed see no "examples/" subdirectory. However, when I run R CMD check and R CMD INSTALL on the package source, I get no warnings about the "examples/" subdirectory. So the package installs without problems, but omits the examples. What do I have to do in order to access the files in "examples/"?

Answer 1

At first I misread your question and thought you were the package author. The problem is that as you noticed examples doesn't get copied in when installed. A solution would be for the package authors to put the folder in /inst/examples instead of /examples. Since you don't have control of that we can create a workaround by downloading the source and then using that instead.

# Downloads the source code for a package
# Extracts it to a temporary directory
downloadAndExtract <- function(package, tdir = tempdir()){
    down <- download.packages(package, destdir = tdir)
    targz <- down[,2]
    untar(targz, exdir = tdir)
    file.path(tdir, package)
}

path <- downloadAndExtract("XX")
filepath <- file.path(path, "examples", "ex.txt")
dat <- read.table(filepath, header = TRUE, sep = "\t")

Clearly this isn't ideal but since you won't find that file in the installed package we need to resort to some sort of workaround...