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 whether
- the position on the search list at which to attach the loaded package. 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 loading is printed, and most often, no errors/warnings are printed if package loading fails.
require(package) both load the package with name
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 loaded packages and do not reload a package which is already loaded. (Furthermore, if the package has a namespace and a name space of that name is already loaded, they work from the existing namespace rather than reloading from the file system. If you want to reload such a package, call
detach(unload = TRUE) or
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.
library is called with no
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 (
lib.loc, the attached packages are searched before the libraries.
library returns (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
require returns (invisibly) a logical indicating whether the required package is available.
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 package 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 package. Naturally, if the package does have any such methods, this will prevent them from being used.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
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
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) # load 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)
Documentation reproduced from R 3.0.1. License: GPL-2.