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\name{as.linnet.SpatialLines}
\alias{as.linnet.SpatialLines}
\alias{coerce,SpatialLines,linnet-method}
\alias{coerce,SpatialLinesDataFrame,linnet-method}
\title{
Convert SpatialLines to Linear Network
}
\description{
Convert an object of class \code{SpatialLines} or
\code{SpatialLinesDataFrame} (from package \pkg{sp}),
representing a collection of polygonal lines,
into an object of class \code{linnet} (from package \pkg{spatstat}),
representing a network.
}
\usage{
as.linnet.SpatialLines(X, \dots, fuse = TRUE)
\S4method{coerce}{SpatialLines,linnet}(from, to = "linnet", strict = TRUE)
\S4method{coerce}{SpatialLinesDataFrame,linnet}(from, to = "linnet",
strict = TRUE)
}
\arguments{
\item{X, from}{
Object of class \code{SpatialLines} or
\code{SpatialLinesDataFrame} to be converted.
}
\item{to}{output object of class \dQuote{linnet}.}
\item{strict}{logical flag. If TRUE, the returned object must be strictly from the target class.}
\item{\dots}{
Ignored.
}
\item{fuse}{
Logical value indicating whether to join different curves
which have a common vertex.
}
}
\details{
This function converts an object of class \code{SpatialLines}
or \code{SpatialLinesDataFrame} into an object of class \code{linnet}.
It is not a method for the \pkg{spatstat} generic function
\code{\link[spatstat]{as.linnet}}, but like other S4 coercion functions for
\pkg{sp} classes to \pkg{spatstat} classes, it may be called directly as a function.
An object of class {SpatialLines}
or \code{SpatialLinesDataFrame} (from package \pkg{sp}) represents
a list of lists of the coordinates of lines, such as a list of all roads in
a city. An object of class \code{linnet} in the \pkg{spatstat} package
represents a linear network, such as a road network.
If \code{fuse=FALSE}, each \dQuote{Line} object in \code{X}
will be treated as if it were disconnected from the others.
The result is a network that consists of many disconnected sub-networks,
equivalent to the list of \dQuote{Line} objects.
If \code{fuse=TRUE} (the default), the code will
search for identical pairs of vertices occurring in different
\dQuote{Line} objects, and will treat them as identical vertices,
effectively joining the two \dQuote{Line} objects at this common
vertex.
If \code{X} belongs to class \code{SpatialLinesDataFrame},
the associated columns of data in the auxiliary data frame
\code{slot(X, "data")} will be copied to the output as the marks
attached to the line segments of the network. See the Examples.
}
\value{
An object of class \code{linnet}.
}
\author{
Adrian Baddeley.
}
\seealso{
\code{\link[spatstat]{as.linnet}}
}
\examples{
run <- FALSE
if(require(spatstat, quietly=TRUE)) run <- TRUE
if (run) {
dname <- system.file("shapes", package="maptools")
fname <- file.path(dname, "fylk-val.shp")
fylk <- readShapeSpatial(fname, proj4string=CRS("+proj=utm +zone=33 +ellps=WGS84"))
is.projected(fylk)
}
if (run) {
L <- as(fylk, "linnet")
print(max(vertexdegree(L)))
}
if (run) {
L0 <- as.linnet.SpatialLines(fylk, fuse=FALSE)
print(max(vertexdegree(L0)))
}
if (run) {
## extract data associated with each network segment
head(marks(as.psp(L)))
}
if (run) {
fname <- file.path(dname, "fylk-val-ll.shp")
fylk <- readShapeSpatial(fname, proj4string=CRS("+proj=longlat +ellps=WGS84"))
is.projected(fylk)
}
if (run) {
try(L <- as(fylk, "linnet"))
}
}
\keyword{spatial}
\keyword{manip}
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