| library {base} | R Documentation |
library and require load and attach add-on packages.
library(package, help, pos = 2, lib.loc = NULL,
character.only = FALSE, logical.return = FALSE,
warn.conflicts, quietly = FALSE,
verbose = getOption("verbose"),
mask.ok, exclude, include.only,
attach.required = missing(include.only))
require(package, lib.loc = NULL, quietly = FALSE,
warn.conflicts,
character.only = FALSE,
mask.ok, exclude, include.only,
attach.required = missing(include.only))
conflictRules(pkg, mask.ok = NULL, exclude = NULL)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 namespace. 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 to .libPaths(). Non-existent library trees are silently ignored. |
character.only |
a logical indicating whether package or help can be assumed to be character strings. |
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. A conflict is a function masking a function, or a non-function masking a non-function. The default is TRUE unless specified as FALSE in the conflicts.policy option. |
verbose |
a logical. If TRUE, additional diagnostics are printed. |
quietly |
a logical. If TRUE, no message confirming package attaching is printed, and most often, no errors/warnings are printed if package attaching fails. |
pkg |
character string naming a package. |
mask.ok |
character vector of names of objects that can mask objects on the search path without signaling an error when strict conflict checking is enabled |
exclude, include.only |
character vector of names of objects to exclude or include in the attached frame. Only one of these arguments may be used in a call to library or require. |
attach.required |
logical specifying whether required packages listed in the Depends clause of the DESCRIPTION file should be attached automatically. |
library(package) and require(package) both load the namespace of the
package with name package and attach it on the search list. require
is designed for use inside other functions; it returns FALSE and gives
a warning (rather than an error as 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
detach(unload = TRUE) or unloadNamespace first.) If you want to
load a package without attaching it on the search list, see
requireNamespace.
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 authors.
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.) 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 (NULL) for lib.loc, the
attached packages are searched before the libraries.
Normally library returns (invisibly) the list of attached packages,
but TRUE or FALSE if logical.return is TRUE. When called as
library() it returns an object of class "libraryIQR", and for
library(help=), one of class "packageInfo".
require returns (invisibly) a logical indicating whether the required
package is available.
Handling of conflicts depends on the setting of the conflicts.policy
option. If this option is not set, then conflicts result in warning
messages if the argument warn.conflicts is TRUE. If the option is
set to the character string "strict", then all unresolved conflicts
signal errors. Conflicts can be resolved using the mask.ok, exclude,
and include.only arguments to library and require. Defaults for
mask.ok and exclude can be specified using conflictRules.
If the conflicts.policy option is set to the string "depends.ok"
then conflicts resulting from attaching declared dependencies will not
produce errors, but other conflicts will. This is likely to be the best
setting for most users wanting some additional protection against
unexpected conflicts.
The policy can be tuned further by specifying the conflicts.policy
option as a named list with the following fields:
error:
logical; if TRUE treat unresolved conflicts as errors.
warn:
logical; unless FALSE issue a warning message when conflicts are
found.
generics.ok:
logical; if TRUE ignore conflicts created by defining S4 generics for
functions on the search path.
depends.ok:
logical; if TRUE do not treat conflicts with required packages as
errors.
can.mask:
character vector of names of packages that are allowed to be masked.
These would typically be base packages attached by default.
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
namespace 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 recorded as accepted.
Free or Open Source Software (FOSS, e.g.
https://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 being used.
library and 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 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. 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 x86_64-unknown-linux-gnu OS).
The package name given to library and 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 macOS.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
.libPaths, .packages.
attach, detach, search, objects, autoload, requireNamespace,
library.dynam, data, install.packages and installed.packages;
INSTALL, REMOVE.
The initial set of packages attached is set by
options(defaultPackages=): see also Startup.
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)──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────
[Package base version 4.3.1 ]
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