cran - Offline install of R package and dependencies

Question

Suppose I need to install a number of packages on a (Linux) machine that does not have an internet connection. Let's say that I downloaded a copy of cran and burned it on a DVD that I bring to the offline location:

wget ftp://cran.r-project.org/pub/R/src/contrib/*.tar.gz

I can even add a PACKAGES file that contains an overview of all the source packages and their dependencies:

library(tools)
write_PACKAGES()

How could I use this offline to install a source package in such a way that dependencies are resolved and installed from the local files as well? For example, someone wants to install package ggplot2, which has a fairly deep dependency structure. Assume the source package of ggplot2 and all of its dependencies are available as source packages in the current working directory. If I do:

install.packages("ggplot2_0.9.1.tar.gz", repos=NULL)

This results in an error, because the dependencies are not resolved at all. Alternatively:

install.packages(list.files(pattern="*.tar.gz"), repos=NULL)

However this also ignores the dependency structure, and tries to install packages in alphabetical order, which will also fail.

I looked into available.packages and contrib.url but I just can't find an example of installing a source package from a local file including it's dependencies.

Answer 1

The correct answer was given by Joshua Ulrich in the comment on the question:

The key is prefixing the argument to either repos or contriburl with file://. So in Unixy systems one could do:

install.packages("ggplot2", contriburl="file:///path/to/packages/")

This assumes that all required source packages, as well as a PACKAGES index file is available in /path/to/packages. If no PACKAGES file is present, this should be generated first using:

library(tools)
write_PACKAGES("/path/to/packages/")

which will generate an index of all source packages found in this directory. Note that in the example, there are 3 slashes behind the file: prefix. The third slash indicates a path relative to the root of the file system.

The difference between the repos and contriburl argument is that repos will append another /src/contrib to the path specified, as this is usually where source packages are located on an official CRAN repository mirror.