Loading/Attaching and Listing of Packages
require load and attach add-on packages.
library(package, help, pos = 2, lib.loc = NULL, character.only = FALSE, logical.return = FALSE, warn.conflicts = TRUE, quietly = FALSE, verbose = getOption("verbose"))require(package, lib.loc = NULL, quietly = FALSE, warn.conflicts = TRUE, character.only = FALSE)
- package, help
- the name of a package, given as a name or
literal character string, or a character string, depending on
- the position on the search list at which to attach the
loaded namespace. Can also be the name of a position on the current
search list as given by
- a character vector describing the location of R
library trees to search through, or
NULL. The default value of
NULLcorresponds to all libraries currently known to
.libPaths(). Non-existent library trees are silently ignored.
- a logical indicating whether
helpcan be assumed to be character strings.
- logical. If it is
TRUEis returned to indicate success.
- logical. If
TRUE, warnings are printed about
conflictsfrom attaching the new package. A conflict is a function masking a function, or a non-function masking a non-function.
- a logical. If
TRUE, additional diagnostics are printed.
- a logical. If
TRUE, no message confirming package attaching is printed, and most often, no errors/warnings are printed if package attaching fails.
require(package) both load the
namespace of the package with name
package and attach it on the
require is designed for use inside other
functions; it returns
FALSE and gives a warning (rather than an
library() does by default) if the package does not
exist. Both functions check and update the list of currently attached
packages and do not reload a namespace which is already loaded. (If
you want to reload such a package, call
unloadNamespace first.) If you want to load a
package without attaching it on the search list, see
To suppress messages during the loading of packages use
suppressPackageStartupMessages: this will suppress all
messages from R itself but not necessarily all those from package
library is called with no
argument, it lists all available packages in the libraries specified
lib.loc, and returns the corresponding information in an
object of class
"libraryIQR". (The structure of this class may
change in future versions.) Use
.packages(all = TRUE) to
obtain just the names of all available packages, and
installed.packages() for 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 (
lib.loc, the attached packages are searched before the libraries.
libraryreturns (invisibly) the list of attached packages, but
TRUE. When called as
library()it returns an object of class
"libraryIQR", and for
library(help=), one of class
requirereturns (invisibly) a logical indicating whether the required package is available.
require can only load/attach an
installed package, and this is detected by having a
DESCRIPTION file containing a Built: field.
Under Unix-alikes, the code checks that the package was installed
under a similar operating system as given by
(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. If sub-architectures are used, the OS similarity is not
checked since the OS used to build may differ (e.g.
i386-pc-linux-gnu code can be built on an
The package name given to
require must match
the name given in the package's DESCRIPTION file exactly, even
on case-insensitive file systems such as are common on Windows and
Some packages have restrictive licenses, and there is a mechanism to
allow users to be aware of such licenses. If
getOption("checkPackageLicense") == TRUE, then at first
use of a package with a not-known-to-be-FOSS (see below) license the
user is asked to view and accept the license: a list of accepted
licenses is stored in file ~/.R/licensed. In a non-interactive
session it is an error to use such a package whose license has not
already been accepted. Free or Open Source Software (FOSS, e.g.,
http://en.wikipedia.org/wiki/FOSS) packages are determined by
the same filters used by
available.packages but applied
to just the current package, not its dependencies. There can also be a site-wide file R_HOME/etc/licensed.site of
packages (one per line).
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 namespace is loaded after methods and re-defined functions
(implicit generics) are excluded from the list of conflicts.
The caching and check for conflicts require looking for a pattern of
objects; the search may be avoided by defining an object
.noGenerics (with any value) in the namespace. Naturally, if the
package does have any such methods, this will prevent them from
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
The initial set of packages attached is set by
options(defaultPackages=): see also
library() # list all available packages library(lib.loc = .Library) # list all packages in the default library library(help = splines) # documentation on package 'splines' library(splines) # attach package 'splines' require(splines) # the same search() # "splines", too detach("package:splines") # if the package name is in a character vector, use pkg <- "splines" 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())) require(nonexistent) # FALSE ## Not run: # ## if you want to mask as little as possible, use # library(mypkg, pos = "package:base") # ## End(Not run)