Question

In the documentation, R suggests that raw data files (not Rdata nor Rda) should be placed in inst/extdata/

From the first paragraph in: http://cran.r-project.org/doc/manuals/R-exts.html#Data-in-packages

The data subdirectory is for data files, either to be made available
via lazy-loading or for loading using data(). (The choice is made by
the ‘LazyData’ field in the DESCRIPTION file: the default is not to do
so.) It should not be used for other data files needed by the package,
and the convention has grown up to use directory inst/extdata for such
files.

So, I have moved all of my raw data into this folder, but when I build and reload the package and then try to access the data in a function with (for example):

read.csv(file=paste(path.package("my_package"),"/inst/extdata/my_raw_data.csv",sep="")) 
# .path.package is now path.package in R 3.0+

I get the “cannot open file” error.

However, it does look like there is a folder called /extdata in the package directory with the files in it (post-build and install). What’s happening to the /inst folder?

Does everything in the /inst folder get pushed into the / of the package?

Answer 1

You were both very close and essentially had this. A formal reference from ‘Writing R Extensions’ is:

1.1.3 Package subdirectories

[…]

The contents of the inst subdirectory will be copied recursively
to the installation directory. Subdirectories of inst should not
interfere with those used by R (currently, R, data, demo,
exec, libs, man, help, html and Meta, and earlier versions
used latex, R-ex). The copying of the inst happens after src
is built so its Makefile can create files to be installed. Prior to
R 2.12.2, the files were installed on POSIX platforms with the permissions in the package sources, so care should be taken to ensure
these are not too restrictive: R CMD build will make suitable
adjustments. To exclude files from being installed, one can specify a
list of exclude patterns in file .Rinstignore in the top-level
source directory. These patterns should be Perl-like regular
expressions (see the help for regexp in R for the precise details),
one per line, to be matched(10) against the file and directory paths,
e.g. doc/.*[.]png$ will exclude all PNG files in inst/doc based on
the (lower-case) extension.