save/load/install a list of your currently installed R packages

restore_packages.R

# restore_packages.R
#
# installs each package from the stored list of packages
# source: http://hlplab.wordpress.com/2012/06/01/transferring-installed-packages-between-different-installations-of-r/

load("~/installed_packages.rda")

for (count in 1:length(installedpackages)) {
    install.packages(installedpackages[count])
}

store_packages.R

# store_packages.R
#
# stores a list of your currently installed packages
# source: http://hlplab.wordpress.com/2012/06/01/transferring-installed-packages-between-different-installations-of-r/

tmp = installed.packages()
installedpackages = as.vector(tmp[is.na(tmp[,"Priority"]), 1])
save(installedpackages, file="~/installed_packages.rda")