zpackages: Listing of Packages
In robertzk/monadicbase: The R Base Package

Description Usage Arguments Details Value Note Author(s) See Also Examples

.packages returns information about package availability.

1	.packages(all.available = FALSE, lib.loc = NULL)

`all.available`	logical; if `TRUE` return a character vector of all available packages in `lib.loc`.
`lib.loc`	a character vector describing the location of R library trees to search through, or `NULL`. The default value of `NULL` corresponds to `.libPaths()`.

.packages() returns the names of the currently attached packages invisibly whereas .packages(all.available = TRUE) gives (visibly) all packages available in the library location path lib.loc.

For a package to be regarded as being ‘available’ it must have valid metadata (and hence be an installed package). However, this will report a package as available if the metadata does not match the directory name: use find.package to confirm that the metadata match or installed.packages for a much slower but more comprehensive check of ‘available’ packages.

A character vector of package base names, invisible unless all.available = TRUE.

.packages(all.available = TRUE) is not a way to find out if a small number of packages are available for use: not only is it expensive when thousands of packages are installed, it is an incomplete test. See the help for find.package for why require should be used.

R core; Guido Masarotto for the all.available = TRUE part of .packages.

library, .libPaths, installed.packages.

(.packages())               # maybe just "base"
.packages(all.available = TRUE) # return all available as character vector
require(splines)
(.packages())               # "splines", too
detach("package:splines")