The R Project SVN R

\name{assign}
\alias{assign}
\alias{<-}
\alias{<<-}
\alias{->}
\alias{->>}
\title{Assign a Value to a Name}
\description{
  Assign a value to a name in an environment.
}
\usage{
assign(x, value, pos = -1, envir = pos.to.env(pos),
       inherits = FALSE, immediate = TRUE)
x <- value
x <<- value
value -> x
value ->> x
}
\arguments{
  \item{x}{a variable name (given as a quoted string).}
  \item{value}{a value to be assigned to \code{x}.}
  \item{pos}{an index into the search list which determines which
    environment the assignment is to take place in.  A character string
    may also be used.  The environment can also be specified directly
    with \code{envir}.}
  \item{envir}{the \code{\link{environment}} in which to assign.  The
    default is the environment where the call to \code{assign} takes
    place.}
  \item{inherits}{should the enclosing frames of the environment be
    inspected?}
  \item{immediate}{an ignored compatibility feature.}
}
\value{
  This function is invoked for its side effect, which is assigning
  \code{value} to the variable \code{x}.  If no \code{envir} is
  specified, then the assignment takes place in the currently active
  environment.

  If \code{inherits} is \code{TRUE}, enclosing environments of the supplied
  environment are searched until the variable \code{x} is encountered.
  The value is then assigned in the environment in which the variable is
  encountered.  If the symbol is not encountered then assignment takes
  place in the user's workspace (the global environment).

  If \code{inherits} is \code{FALSE}, assignment takes place in the
  initial frame of \code{envir}.


}
\details{
  The arrow forms of assignment provide shortcut ways to carry out
  assignment.  The \code{<-} and \code{->} forms carry out assignment
  in the local environment frame, while the \code{<<-} and \code{->>}
  forms cause a search to made through the environment for an existing
  definition of the variable being assigned.  If such a variable is
  found then its value is redefined, otherwise assignment takes place
  globally.

  Note that the action of \code{<<-} and \code{->>} differs from that in
  the S language, but is useful in conjunction with the scoping rules of
  R.

  \code{assign} does not dispatch assignment methods, so it cannot be
  used to set elements of vectors, names, attributes, etc.
  }
\seealso{
  \code{\link{get}},
  \code{\link{exists}},
  \code{\link{environment}}.}
\examples{
for(i in 1:6) { #-- Create objects  'r1', 'r2', ... 'r6' --
 nam <- paste("r",i, sep=".")
 assign(nam, 1:i)
}
ls(pat="^r..$")

##-- Global assignment within a function:
myf <- function(x) {
 innerf <- function(x) assign("Global.res", x^2, env = .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

}
\keyword{data}