base (version 3.3)

assign: Assign a Value to a Name

Description

Assign a value to a name in an environment.

Usage

assign(x, value, pos = -1, envir = as.environment(pos), inherits = FALSE, immediate = TRUE)

Arguments

x

a variable name, given as a character string. No coercion is done, and the first element of a character vector of length greater than one will be used, with a warning.

value

a value to be assigned to x.

pos

where to do the assignment. By default, assigns into the current environment. See ‘Details’ for other possibilities.

envir

the environment to use. See ‘Details’.

inherits

should the enclosing frames of the environment be inspected?

immediate

an ignored compatibility feature.

Value

This function is invoked for its side effect, which is assigning value to the variable x. If no envir is specified, then the assignment takes place in the currently active environment.If inherits is TRUE, enclosing environments of the supplied environment are searched until the variable x is encountered. The value is then assigned in the environment in which the variable is encountered (provided that the binding is not locked: see lockBinding: if it is, an error is signaled). If the symbol is not encountered then assignment takes place in the user's workspace (the global environment).If inherits is FALSE, assignment takes place in the initial frame of envir, unless an existing binding is locked or there is no existing binding and the environment is locked (when an error is signaled).

Details

There are no restrictions on the name given as x: it can be a non-syntactic name (see make.names).

The pos argument can specify the environment in which to assign the object in any of several ways: as -1 (the default), as a positive integer (the position in the search list); as the character string name of an element in the search list; or as an environment (including using sys.frame to access the currently active function calls). The envir argument is an alternative way to specify an environment, but is primarily for back compatibility.

assign does not dispatch assignment methods, so it cannot be used to set elements of vectors, names, attributes, etc.

Note that assignment to an attached list or data frame changes the attached copy and not the original object: see attach and with.

References

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

See Also

<-, get, exists, environment.

Examples

for(i in 1:6) { #-- Create objects  'r.1', 'r.2', ... 'r.6' --
    nam <- paste("r", i, sep = ".")
    assign(nam, 1:i)
}
ls(pattern = "^r..$")

##-- Global assignment within a function:
myf <- function(x) {
    innerf <- function(x) assign("Global.res", x^2, envir = .GlobalEnv)
    innerf(x+1)
}
myf(3)
Global.res # 16

a <- 1:4
assign("a[1]", 2)
a[1] == 2          # FALSE
get("a[1]") == 2   # TRUE