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 attached by library.
detach(name, pos = 2L, unload = FALSE, character.only = FALSE,
force = FALSE)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.
Index position in search() of the database to
detach. When name is a number, pos = name
is used.
A logical value indicating whether or not to attempt to
unload the namespace when a package is being detached. If the
package has a namespace and unload is TRUE, then
detach will attempt to unload the namespace via
unloadNamespace: if the namespace is imported by
another namespace or unload is FALSE, no unloading
will occur.
a logical indicating whether name
can be assumed to be a character string.
logical: should a package be detached even though other attached packages depend on it?
The return value is invisible. It is NULL when a
package is detached, otherwise the environment which was returned by
attach when the object was attached (incorporating any
changes since it was attached).
detach() without an argument removes the first item on the
search path after the workspace. It is all too easy to call it too
many or too few times, or to not notice that the search path has
changed since an attach call.
Use of attach/detach is best avoided in functions (see
the help for attach) and in interactive use and scripts
it is prudent to detach by name.
This is 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
namespace is loaded, it attaches the exports of the already loaded
namespace. So detaching and re-attaching a package may not refresh
some or all components of the package, and is inadvisable.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
attach, library, search,
objects, unloadNamespace,
library.dynam.unload .
# NOT RUN {
require(splines) # package
detach(package:splines)
## or also
library(splines)
pkg <- "package:splines"
# }
# NOT RUN {
detach(pkg, character.only = TRUE)
## careful: do not do this unless 'splines' is not already attached.
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])
detach(name, character.only = TRUE)
}
attach_and_detach(women, pos = 3)
# }