library(name, help = NULL, lib.loc = .lib.loc, character.only = FALSE, logical.return = FALSE) require(name, quietly = FALSE) provide(name) library.dynam(chname) .packages() .lib.loc .Library .Provided
name, help
|
name or character string giving the name of a
package
|
lib.loc
| a character vector describing the location of R library trees to search through. |
character.only
|
a logical indicating whether name or
help can be assumed to be character strings
|
quietly
|
if TRUE , a warning will not be printed if the
package cannot be found.
|
chname
| a character string naming a shared library to load |
library(name)
and require(name)
both load the package
with name name
.
require
is designed for use inside other functions; it returns
FALSE
and optionally gives a warning, rather than giving an
error, 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. require
also
checks the list .Provided
.
provide
allows code to register services that it provides. The
argument is stored in the list .Provided
. provide
returns FALSE
if the name was already present in
.Provided
or among the packages in search()
. The main
use for provide
is when multiple packages share code. This is
most likely when the code implements features present in S(-PLUS) but
not in R. For example, the spline functions ns
, bs
and
so on are not included in the R distribution. A package containing
these functions can use provide(splines)
to register this fact.
Another package that needs the functions can execute
require(splines)
rather than library(splines)
to load
the spline package only if their functionality is not already available.
If library
is called with no argument, it gives a list of all
available packages. library(help = name)
prints information on
the package name
, typically by listing the most important user
level objects it contains.
library.dynam
loads the specified (shared) object file if it
has not been loaded already. It is designed to be used inside a
package rather than at the command line. The system-specific
extension for shared libraries (e.g., ``.so'' on Unix systems) should
not be added.
.packages()
returns the ``base names'' of the currently attached
packages.
.Library
is a character string giving the location of the
default library, the ``library'' subdirectory of RHOME
.
.lib.loc
is a character vector with the locations of all
library trees that R should use. It is initialized at startup from
the environment variable RLIBS
, which should be a
colon-separated list of directories at which R library trees are
rooted, and .Library
.
library
returns the list of loaded packages (or TRUE
if
logical.return
is TRUE
).
require
returns a logical indicating whether the required
package is available.
eda
and mva
.
A package consists of a subdirectory containing a `TITLE' and `INDEX' file, and subdirectories `R', `man' and optionally `src', `src-c', `data', and `exec'.
The `TITLE' file contains a line giving the name of the package and a brief description. `INDEX' contains a line for each sufficiently interesting object in the package, giving its name and a description (functions such as print methods not usually called explicitly might not be included).
The `R' subdirectory contains R code files with names beginning
with lowercase letters. One of these files should use
library.dynam()
to load any necessary compiled code.
The `man' subdirectory should contain R documentation files for the objects in the package.
Source and a Makefile for the compiled code is in `src', and a
pure C version of the source should be in `src-c'. In the common
case when all the source is in C it may be convenient to make one of
these directories a symbolic link to the other. The Makefile will be
passed various machine-dependent compile and link flags, examples of
which can be seen in the eda
package.
The `data' subdirectory is for additional data files the package
makes available for loading using data()
. Note that (at least
currently) all such files are in fact R code files, and must have the
extension `.R'.
Finally, `exec' could contain executables, typically (shell or Perl) scripts, the package needs. Note that this mechanism currently only is experimental.
R INSTALL pkg
, where pkg
is the
directory containing the package. If you want to install into the
library tree lib
instead of the default one, use
R INSTALL pkg lib
.
To remove the package pkg
from the default library or the
library lib
, do R REMOVE pkg
or R REMOVE pkg lib
,
respectively.
attach
, detach
, search
,
objects
, autoload
.
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 require(nonexistent) # FALSE