library(name, help = NULL, lib.loc = .lib.loc) library.dynam("name.so") provide(name) require(name, quietly = FALSE) .lib.loc .library(chname, lib.loc = .lib.loc, logical.return = FALSE) .Provided
name, chname
|
the name of a package. chname must be a
character string whereas name may also be a name .
|
lib.loc
| a character vector describing the location of R library trees to search through. |
quietly
|
if TRUE , a warning will not be printed if the
package cannot be found.
|
library
and require
both load a package.
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.
.library
is an auxiliary function which is used by almost all
others.
The functions called with no argument return useful information.
library()
gives a list of available packages;
.library()
returns the ``base names'' of the currently attached
packages;
provide()
returns .Provided
.
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.
.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 the R ``home''
directory RHOME
.
library(help = name)
prints a list of objects in package "name".
eda
and mva
.
A package consists of a subdirectory containing a TITLe
and INDEX
file, and subdirectories funs
, man
and
optionally src
, src-c
, and data
. 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 funs
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.
Finally, the data
subdirectory is for additional data files the
package makes available for loading using data()
.
R INSTALL pkg
, where pkg
is the
directory containing the package. If you want to install to the library
tree lib
instead of the default one, use R INSTALL pkg lib
.
library
returns the list of loaded libraries;
require
returns a boolean value indicating whether the required
package is available.
attach
, detach
, search
,
objects
, autoload
.