| attach {base} | R Documentation |
Attach Set of R Objects to Search Path
Description
The database is attached to the R search path. This means that the database is searched by R when evaluating a variable, so objects in the database can be accessed by simply giving their names.
Usage
attach(what, pos = 2, name = deparse(substitute(what)))
Arguments
what |
“database”. This may currently be a |
pos |
integer specifying position in |
name |
alternative way to specify the database to be attached. |
Details
When evaluating a variable or function name R searches for
that name in the databases listed by search. The first
name of the appropriate type is used.
By attaching a data frame to the search path it is possible to refer
to the variables in the data frame by their names alone, rather than
as components of the data frame (eg in the example below,
height rather than women$height).
By default the database is attached in position 2 in the search path,
immediately after the user's workspace and before all previously
loaded packages and previously attached databases. This can be altered
to attach later in the search path with the pos option, but you
cannot attach at pos=1.
Note that by default assignment is not performed in an attached
database. Attempting to modify a variable or function in an attached
database will actually create a modified version in the user's
workspace (the R global environment). For this reason attach
can lead to confusion.
Value
The environment is returned invisibly with a
"name" attribute.
See Also
library, detach, search,
objects, environment.
Examples
data(women)
summary(women$height) ## refers to variable `height' in the dataframe
attach(women)
summary(height) ## The same variable now available by name
height<-height*2.54 ## Don't do this. It creates a new variable
detach("women")
summary(height) ## The new variable created by modifying `height'
rm(height)