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\name{as.psp}
\alias{as.psp.Line}
\alias{coerce,Line,psp-method}
\alias{as.psp.Lines}
\alias{coerce,Lines,psp-method}
\alias{as.psp.SpatialLines}
\alias{coerce,SpatialLines,psp-method}
\alias{as.psp.SpatialLinesDataFrame}
\alias{coerce,SpatialLinesDataFrame,psp-method}
\alias{as.SpatialLines.psp}
\alias{coerce,psp,SpatialLines-method}
\title{Coercion between sp objects and spatstat psp objects}
\description{
Functions to convert between \pkg{spatstat}s planar segment pattern (\code{psp})
format and various \pkg{sp} line formats. S4-style \code{as()} coercion can be
used as well.
}
\section{Methods}{
\describe{
\item{coerce}{\code{signature(from = "Line", to = "psp")}}
\item{coerce}{\code{signature(from = "Lines", to = "psp")}}
\item{coerce}{\code{signature(from = "SpatialLines", to = "psp")}}
\item{coerce}{\code{signature(from = "SpatialLinesDataFrame", to = "psp")}}
\item{coerce}{\code{signature(from = "psp", to = "SpatialLines")}}
}
}
\usage{
as.psp.Line(from, \dots, window=NULL, marks=NULL, fatal)
as.psp.Lines(from, \dots, window=NULL, marks=NULL, fatal)
as.psp.SpatialLines(from, \dots, window=NULL, marks=NULL, characterMarks
= FALSE, fatal)
as.psp.SpatialLinesDataFrame(from, \dots, window=NULL, marks=NULL, fatal)
as.SpatialLines.psp(from)
}
\arguments{
\item{from}{object to coerce from}
\item{\dots}{ignored}
\item{window}{window of class \code{owin} as defined in the spatstat package}
\item{marks}{marks as defined in the spatstat package}
\item{characterMarks}{default FALSE, if TRUE, do not convert NULL marks to factor from character}
\item{fatal}{formal coercion argument; ignored}
}
\section{Warning}{
In \pkg{spatstat} all spatial objects are assumed to be planar. This means
that \pkg{spatstat} is not designed to work directly with geographic
(longitude and latitude) coordinates. If a \pkg{sp} object is declared to
have geographic (unprojected) coordinates \pkg{maptools} refuses to convert
directly to \pkg{spatstat} format. Rather, these should be projected first
using e.g. \code{\link[sp]{spTransform}}. If you know what you are doing, and
really want to force coercion, you can overwrite the \code{proj4string} of the
\pkg{sp} object with \code{NA}, \code{proj4string(x) <- CRS(NA)}, which
will fool the system to think that the data is in local planar coordinates.
This is probably not a good idea!
}
\author{Edzer Pebesma \email{edzer.pebesma@uni-muenster.de}, Roger Bivand}
\examples{
run <- FALSE
if (require(spatstat, quietly=TRUE)) run <- TRUE
if (run) {
data(meuse.riv)
mr <- Line(meuse.riv)
mr_psp <- as(mr, "psp")
mr_psp
}
if (run) {
plot(mr_psp)
}
if (run) {
xx_back <- as(mr_psp, "SpatialLines")
plot(xx_back)
}
if (run) {
xx <- readShapeLines(system.file("shapes/fylk-val.shp", package="maptools")[1],
proj4string=CRS("+proj=utm +zone=33 +ellps=WGS84"))
xx_psp <- as(xx["LENGTH"], "psp")
xx_psp
}
if (run) {
plot(xx_psp)
}
if (run) {
xx_back <- as(xx_psp, "SpatialLines")
plot(xx_back)
}
if (run) {
xx <- readShapeLines(system.file("shapes/fylk-val-ll.shp", package="maptools")[1],
proj4string=CRS("+proj=longlat +ellps=WGS84"))
try(xx_psp <- as(xx["LENGTH"], "psp"))
}
}
\keyword{spatial}
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