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\name{addVertices}
\alias{addVertices}
\title{
Add New Vertices to a Linear Network
}
\description{
Adds new vertices to a linear network
at specified locations outside the network.
}
\usage{
addVertices(L, X, join=NULL, joinmarks=NULL)
}
\arguments{
\item{L}{
Existing linear network (object of class \code{"linnet"})
or point pattern on a linear network (object of class \code{"lpp"}).
}
\item{X}{
Point pattern (object of class \code{"ppp"})
specifying the new vertices.
}
\item{join}{
Optional information specifying how to join the new vertices
\code{X} to the existing network. See Details.
If \code{join=NULL} (the default),
the new vertices are simply added to the list of network vertices
without being joined to the rest of the network.
}
\item{joinmarks}{
Optional vector or data frame of marks associated with the
new edges specified by \code{join}.
}
}
\details{
This function adds new vertices to an existing
linear network \code{L}, at specified locations \code{X} outside the 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 are points outside the network,
specified as a point pattern \code{X} (object of class \code{"ppp"}).
The argument \code{join} specifies how to join the new vertices
to the existing network.
\itemize{
\item
If \code{join=NULL} (the default),
the new vertices are simply added to the list of network vertices
without being joined to the rest of the network.
\item
If \code{join} is a vector of integers, then these are taken to be
indices of existing vertices of \code{L} in the order given
in \code{V = vertices(L)}. Then each new vertex \code{X[i]} will be
joined to an existing vertex \code{V[j]} where \code{j = join[i]}.
Each new vertex is joined to exactly one existing vertex.
\item
If \code{join="vertices"} then each new vertex \code{X[i]} is joined
to the nearest existing vertex \code{V[j]}.
Each new vertex is joined to exactly one existing vertex.
\item
If \code{join="nearest"} then each new vertex is projected to the
nearest location along on the network; these locations are inserted
as new vertices of \code{L}; and then each vertex \code{X[i]}
is joined to the corresponding projected point.
Each new vertex is joined to exactly one newly-inserted vertex.
\item
If \code{join} is a point pattern on a network (class \code{"lpp"}),
it must be defined on the same network as \code{L} and it must
consist of the same number of points as \code{X}. The points of
\code{join} will be inserted as new vertices of \code{L},
and then each vertex \code{X[i]} is joined to the corresponding
point \code{join[i]}.
Each new vertex is joined to exactly one newly-inserted vertex.
}
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{insertVertices}} to insert vertices along an existing 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))
L <- simplenet
X <- runifpoint(20, Window(simplenet))
plot(L)
plot(X, add=TRUE, cols="green", pch=16, cex=2)
plot(addVertices(L, X, "nearest"), col="red")
plot(L, add=TRUE, col="grey", lwd=3)
plot(X, add=TRUE, cols="green", pch=16, cex=2)
plot(addVertices(L, X, "vertices"), col="red")
plot(L, add=TRUE, col="grey", lwd=3)
plot(X, add=TRUE, cols="green", pch=16, cex=2)
par(opa)
}
\keyword{spatial}
\keyword{manip}
\concept{Linear network}
|
