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\name{linfun}
\Rdversion{1.1}
\alias{linfun}
\title{
Function on a Linear Network
}
\description{
Create a function on a linear network.
}
\usage{
linfun(f, L)
}
\arguments{
\item{f}{
A \code{function} in the \R language.
}
\item{L}{
A linear network (object of class \code{"linnet"})
on which \code{f} is defined.
}
}
\details{
This creates an object of class \code{"linfun"}.
This is a simple mechanism for handling a function
defined on a linear network, to make it easier to display
and manipulate.
\code{f} should be a \code{function} in the \R language,
with formal arguments \code{x,y,seg,tp} (and optional additional
arguments) where \code{x,y} are
Cartesian coordinates of locations on the linear network,
\code{seg, tp} are the local coordinates.
The function \code{f} should be vectorised: that is,
if \code{x,y,seg,tp} are numeric vectors of the same length
\code{n}, then \code{v <- f(x,y,seg,tp)}
should be a vector of length \code{n}.
\code{L} should be a linear network (object of class \code{"linnet"})
on which the function \code{f} is well-defined.
The result is a function \code{g} in the \R language which belongs to
the special class \code{"linfun"}. There are several methods
for this class including \code{print}, \code{plot}
and \code{\link{as.linim}}.
This function can be called as \code{g(X)}
where \code{X} is an \code{"lpp"} object,
or called as \code{g(x,y)} or \code{g(x,y,seg,tp)} where
\code{x,y,seg,tp} are coordinates. If the original function \code{f}
had additional arguments, then these may be included in the call
to \code{g}, and will be passed to \code{f}.
}
\value{
A function in the \R\ language.
It also belongs to the class \code{"linfun"} which has methods
for \code{plot}, \code{print} etc.
}
\seealso{
\code{\link{methods.linfun}} for methods applicable to
\code{"linfun"} objects.
\code{\link{distfun.lpp}},
\code{\link{nnfun.lpp}}.
}
\examples{
f <- function(x,y,seg,tp) { x+y }
g <- linfun(f, simplenet)
plot(g)
X <- runiflpp(3, simplenet)
g(X)
Z <- as.linim(g)
f <- function(x,y,seg,tp, mul=1) { mul*(x+y) }
g <- linfun(f, simplenet)
plot(g)
plot(g, mul=10)
g(X, mul=10)
Z <- as.linim(g, mul=10)
}
\author{
\adrian
and \rolf
}
\keyword{spatial}
\keyword{math}
\concept{Linear network}
|
