| library {base} | R Documentation |
library and require load add-on packages.
.First.lib is called when a package is loaded;
.Last.lib is called when a package is detached.
.packages returns information about package availability.
.path.package returns information about where a package was
loaded from.
.find.package returns the directory paths of installed
packages.
library(package, help, pos = 2, lib.loc = NULL, character.only = FALSE,
logical.return = FALSE, warn.conflicts = TRUE,
keep.source = getOption("keep.source.pkgs"),
verbose = getOption("verbose"), version)
require(package, quietly = FALSE, warn.conflicts = TRUE,
keep.source = getOption("keep.source.pkgs"),
character.only = FALSE, version, save = TRUE)
.First.lib(libname, pkgname)
.Last.lib(libpath)
.packages(all.available = FALSE, lib.loc = NULL)
.path.package(package = .packages(), quiet = FALSE)
.find.package(package, lib.loc = NULL, quiet = FALSE,
verbose = getOption("verbose"))
.libPaths(new)
.Library
.Autoloaded
package, help |
the name of a package, given as a name or
literal character string, or a character string, depending on
whether character.only is FALSE (default) or
TRUE). |
pos |
the position on the search list at which to attach the
loaded package. Note that .First.lib may attach other
packages, and pos is computed after .First.lib
has been run. Can also be the name of a position on the current
search list as given by search(). |
lib.loc |
a character vector describing the location of R
library trees to search through, or NULL. The default value
of NULL corresponds to all libraries currently known. |
character.only |
a logical indicating whether package or
help can be assumed to be character strings. |
version |
A character string denoting a version number of the package to be loaded. If no version is given, a suitable default is chosen. |
logical.return |
logical. If it is TRUE, FALSE or
TRUE is returned to indicate success. |
warn.conflicts |
logical. If TRUE, warnings are
printed about conflicts from attaching the new
package, unless that package contains an object .conflicts.OK. |
keep.source |
logical. If TRUE, functions “keep their
source” including comments, see argument keep.source to
options. |
verbose |
a logical. If TRUE, additional diagnostics are
printed. |
quietly |
a logical. If TRUE, no message confirming
package loading is printed. |
save |
logical or environment. If TRUE, a call to
require from the source for a package will save the name of
the required package in the variable ".required", allowing
function detach to warn if a required package is
detached. See section ‘Packages that require other packages’ below. |
libname |
a character string giving the library directory where the package was found. |
pkgname |
a character string giving the name of the package. |
libpath |
a character string giving the complete path to the package. |
all.available |
logical; if TRUE return a character vector
of all available packages in lib.loc. |
quiet |
logical.
For .path.package, should this not give warnings or an error
if the package(s) are not loaded?
For .find.package, should this not give warnings or an error
if the package(s) are not found? |
new |
a character vector with the locations of R library trees. |
library(package) and require(package) both load the
package with name package. require is designed for use
inside other functions; it returns FALSE and gives a warning
(rather than an error as library() does) if the package does
not exist. Both functions check and update the list of currently
loaded packages and do not reload code that is already loaded.
For large packages, setting keep.source = FALSE may save quite
a bit of memory.
If library is called with no package or help
argument, it lists all available packages in the libraries specified
by lib.loc, and returns the corresponding information in an
object of class "libraryIQR". The structure of this class may
change in future versions. In earlier versions of R, only the names
of all available packages were returned; use .packages(all =
TRUE) for obtaining these. Note that
installed.packages()
returns even more information.
library(help = somename) computes basic information about the
package somename, and returns this in an object of class
"packageInfo". The structure of this class may change in
future versions. When used with the default value (NULL) for
lib.loc, the loaded packages are searched before the libraries.
.First.lib is called when a package is loaded by
library. It is called with two arguments, the name of the
library directory where the package was found (i.e., the corresponding
element of lib.loc), and the name of the package (in that
order). It is a good place to put calls to library.dynam
which are needed when loading a package into this function (don't call
library.dynam directly, as this will not work if the package
is not installed in a “standard” location). .First.lib
is invoked after the search path interrogated by search()
has been updated, so
as.environment(match("package:name", search())) will return the
environment in which the package is stored. If calling
.First.lib gives an error the loading of the package is
abandoned, and the package will be unavailable. Similarly, if the
option ".First.lib" has a list element with the package's name,
this element is called in the same manner as .First.lib when
the package is loaded. This mechanism allows the user to set package
“load hooks” in addition to startup code as provided by the package
maintainers.
.Last.lib is called when a package is detached. Beware
that it might be called if .First.lib has failed, so it
should be written defensively. (It is called within try,
so errors will not stop the package being detached.)
.packages() returns the “base names” of the currently
attached packages invisibly whereas
.packages(all.available = TRUE) gives (visibly) all
packages available in the library location path lib.loc.
.path.package returns the paths from which the named packages
were loaded, or if none were named, for all currently loaded packages.
Unless quiet = TRUE it will warn if some of the packages named
are not loaded, and given an error if none are. This function is not
meant to be called by users, and its interface might change in future
versions.
.find.package returns the paths to the locations where the
given packages can be found. If lib.loc is NULL, then
then attached packages are searched before the libraries. If a
package is found more than once, the first match is used. Unless
quiet = TRUE a warning will be given about the named packages
which are not found, and an error if none are. If verbose is
true, warnings about packages found more than once are given. This
function is not meant to be called by users, and its interface might
change in future versions.
.Autoloaded contains the “base names” of the packages for
which autoloading has been promised.
.Library is a character string giving the location of the
default library, the ‘library’ subdirectory of R_HOME.
.libPaths is used for getting or setting the library trees that
R knows about (and hence uses when looking for packages). If called
with argument new, the library search path is set to
the existing files in unique(new, .Library) and this is
returned. If given no argument, a character vector with the currently
known library trees is returned.
The library search path is initialized at startup from the environment
variable R_LIBS (which should be a colon-separated list of
directories at which R library trees are rooted) by calling
.libPaths with the directories specified in R_LIBS.
library returns the list of loaded (or available) packages
(or TRUE if logical.return is TRUE).
require returns a logical indicating whether the required
package is available.
The source code for a
package that requires one or more other packages should have a call
to require, preferably near the beginning of the source, and
of course before any code that uses functions, classes or methods
from the other package. The default for argument save will
save the names of all required packages in the environment of the
new package. The saved package names are used by
detach when a package is detached to warn if other
packages still require the detached package. Also, if a package is
installed with saved image (see INSTALL), the saved package
names are used to require these packages when the new package is attached.
library takes some further actions when package methods
is attached (as it is by default). Packages may define formal generic
functions as well as re-defining functions in other packages (notably
base) to be generic, and this information is cached whenever
such a package is loaded after methods and re-defined functions
are excluded from the list of conflicts. The check requires looking
for a pattern of objects; the pattern search may be avoided by
defining an object .noGenerics
(with any value) in the package. Naturally, if the package
does have any such methods, this will prevent them from being used.
library and require can only load an installed
package, and this is detected by having a ‘DESCRIPTION’ file
containing a Built: field. Packages
installed prior to 1.2.0 (released in December 2000) will need to be
re-installed.
Under Unix-alikes, the code checks that the package was installed
under a similar operating system as given by R.version$platform
(the canonical name of the platform under which R was compiled),
provided it contains compiled code. Packages which do not contain
compiled code can be shared between Unix-alikes, but not to other OSes
because of potential problems with line endings and OS-specific help
files.
library and require use the underlying file system
services to locate the libraries, with the result that on
case-sensitive file systems package names are case-sensitive
(i.e., library(foo) is different from
library(Foo)), but they are not distinguished on
case-insensitive file systems such as MS Windows. A warning
is issued if the user specifies a name which isn't a perfect match
to the package name, because future versions of R will require
exact matches.
R core;
Guido Masarotto for the all.available=TRUE part of
.packages.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
attach, detach, search,
objects, autoload,
library.dynam, data,
install.packages and
installed.packages;
INSTALL, REMOVE.
(.packages()) # maybe just "base"
.packages(all = TRUE) # return all available as character vector
library() # list all available packages
library(lib = .Library) # list all packages in the default library
library(help = eda) # documentation on package 'eda'
library(eda) # load package 'eda'
require(eda) # the same
(.packages()) # "eda", too
detach("package:eda")
# if the package name is in a character vector, use
pkg <- "eda"
library(pkg, character.only = TRUE)
detach(pos = match(paste("package", pkg, sep=":"), search()))
require(pkg, character.only = TRUE)
detach(pos = match(paste("package", pkg, sep=":"), search()))
.path.package()
.Autoloaded # maybe "ctest"
.libPaths() # all library trees R knows about
require(nonexistent) # FALSE
## Not run:
## Suppose a package needs to call a shared library named 'fooEXT',
## where 'EXT' is the system-specific extension. Then you should use
.First.lib <- function(lib, pkg) {
library.dynam("foo", pkg, lib)
}
## if you want to mask as little as possible, use
library(mypkg, pos = "package:base")
## End(Not run)