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\name{insertVertices}
\alias{insertVertices}
\title{
Insert New Vertices in a Linear Network
}
\description{
Adds new vertices to a linear network
at specified locations along the network.
}
\usage{
insertVertices(L, \dots)
}
\arguments{
\item{L}{
Linear network (object of class \code{"linnet"})
or point pattern on a linear network (object of class \code{"lpp"}).
}
\item{\dots}{
Additional arguments passed to \code{\link{as.lpp}}
specifying the positions of the new vertices along the network.
}
}
\details{
This function adds new vertices at locations along an existing
linear network.
The argument \code{L} can be either a linear network (class
\code{"linnet"}) or some other object that includes a linear network.
The new vertex locations can be specified either as a
point pattern (class \code{"lpp"} or \code{"ppp"})
or using coordinate vectors \code{x,y} or \code{seg,tp}
or \code{x,y,seg,tp} as explained in the help for \code{\link{as.lpp}}.
This function breaks the existing line segments
of \code{L} into pieces at the locations specified by
the coordinates \code{seg,tp} and creates new vertices at these
locations.
The result is the modified object, with an attribute \code{"id"} such that
the \code{i}th added vertex has become the
\code{id[i]}th vertex of the new network.
}
\value{
An object of the same class as \code{L} representing the result of
adding the new vertices.
The result also has an attribute \code{"id"} as described in Details.
}
\author{
Adrian Baddeley
}
\seealso{
\code{\link{addVertices}} to create new vertices at locations which
are not yet on the network.
\code{\link{as.lpp}},
\code{\link{linnet}},
\code{\link{methods.linnet}},
\code{\link{joinVertices}},
\code{\link{thinNetwork}}.
}
\examples{
opa <- par(mfrow=c(1,3), mar=rep(0,4))
simplenet
plot(simplenet, main="")
plot(vertices(simplenet), add=TRUE)
# add two new vertices at specified local coordinates
L <- insertVertices(simplenet, seg=c(3,7), tp=c(0.2, 0.5))
L
plot(L, main="")
plot(vertices(L), add=TRUE)
id <- attr(L, "id")
id
plot(vertices(L)[id], add=TRUE, pch=16)
# add new vertices at three randomly-generated points
X <- runiflpp(3, simplenet)
LL <- insertVertices(simplenet, X)
plot(LL, main="")
plot(vertices(LL), add=TRUE)
ii <- attr(LL, "id")
plot(vertices(LL)[ii], add=TRUE, pch=16)
par(opa)
}
\keyword{spatial}
\keyword{manip}
|
