detach {base}

R Documentation

Detach Objects from the Search Path

Description

Detach a database, i.e., remove it from the search() path of available R objects. Usually, this is either a data.frame which has been attached or a package which was required previously.

Usage

detach(name, pos = 2, unload = FALSE)

Arguments

name	The object to detach. Defaults to search()[pos]. This can be an unquoted name or a character string but not a character vector. If a number is supplied this is taken as pos.
pos	Index position in search() of database to detach. When name is a number, pos = name is used.
unload	A logical value indicating whether or not to attempt to unload the namespace and S4 methods when a package is being detached. If the package has a namespace and unload is TRUE, then detach will attempt to unload the namespace and remove any S4 methods defined by the package. If the namespace is in use or unload is FALSE, no unloading will occur.

Details

This most commonly used with a single number argument referring to a position on the search list, and can also be used with a unquoted or quoted name of an item on the search list such as package:tools.

If a package has a namespace, detaching it does not by default unload the namespace (and may not even with unload=TRUE), and detaching will not in general unload any dynamically loaded compiled code (DLLs). Further, registered S3 methods from the namespace will not be removed. If you use library on a package whose name space is loaded, it attaches the exports of the loaded name space. So detaching and re-attaching a package may not refresh some or all components of the package, and is inadvisable.

Value

The attached database is returned invisibly, either as data.frame or as list.

Note

You cannot detach either the workspace (position 1) or the base package (the last item in the search list).

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

attach, library, search, objects, unloadNamespace, library.dynam.unload .

Examples

require(splines) # package
detach(package:splines)
## could equally well use detach("package:splines")
## but NOT  pkg <- "package:splines"; detach(pkg)
## Instead, use
library(splines)
pkg <- "package:splines"
detach(pos = match(pkg, search()))

## careful: do not do this unless 'splines' is not already loaded.
library(splines)
detach(2) # 'pos' used for 'name'

## an example of the name argument to attach
## and of detaching a database named by a character vector
attach_and_detach <- function(db, pos=2)
{
   name <- deparse(substitute(db))
   attach(db, pos=pos, name=name)
   print(search()[pos])
   eval(substitute(detach(n), list(n=name)))
}
attach_and_detach(women, pos=3)

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