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\name{as.lpp}
\Rdversion{1.1}
\alias{as.lpp}
\title{
Convert Data to a Point Pattern on a Linear Network
}
\description{
Convert various kinds of data to a point pattern on a linear network.
}
\usage{
as.lpp(x=NULL, y=NULL, seg=NULL, tp=NULL, \dots,
marks=NULL, L=NULL, check=FALSE, sparse)
}
\arguments{
\item{x,y}{
Vectors of cartesian coordinates, or any data
acceptable to \code{\link[grDevices]{xy.coords}}.
Alternatively \code{x} can be a point pattern
on a linear network (object of class \code{"lpp"})
or a planar point pattern (object of class \code{"ppp"}).
}
\item{seg,tp}{
Optional local coordinates. Vectors of the same length
as \code{x,y}. See Details.
}
\item{\dots}{Ignored.}
\item{marks}{
Optional marks for the point pattern.
A vector or factor with one entry for each point,
or a data frame or hyperframe with one row for each point.
}
\item{L}{
Linear network (object of class \code{"linnet"})
on which the points lie.
}
\item{check}{
Logical. Whether to check the validity of the spatial coordinates.
}
\item{sparse}{
Optional logical value indicating whether to store the
linear network data in a sparse matrix representation or not.
See \code{\link{linnet}}.
}
}
\details{
This function converts data in various formats into a point pattern
on a linear network (object of class \code{"lpp"}).
The possible formats are:
\itemize{
\item
\code{x} is already a point pattern on a linear network
(object of class \code{"lpp"}).
Then \code{x} is returned unchanged.
\item
\code{x} is a planar point pattern (object of class \code{"ppp"}).
Then \code{x} is converted to a point pattern on the linear network
\code{L} using \code{\link{lpp}}.
\item
\code{x,y,seg,tp} are vectors of equal length.
These specify that the \code{i}th point has Cartesian coordinates
\code{(x[i],y[i])}, and lies on segment number \code{seg[i]} of the
network \code{L}, at a fractional position \code{tp[i]} along that
segment (with \code{tp=0} representing one endpoint and
\code{tp=1} the other endpoint of the segment).
\item
\code{x,y} are missing and \code{seg,tp} are vectors of equal length
as described above.
\item
\code{seg,tp} are \code{NULL}, and \code{x,y} are data in a format
acceptable to \code{\link[grDevices]{xy.coords}} specifying the
Cartesian coordinates.
\item
Only the arguments \code{x} and \code{L} are given,
and \code{x} is a data frame with one of the following types:
\itemize{
\item two columns labelled \code{seg,tp} interpreted as local
coordinates on the network.
\item two columns labelled \code{x,y} interpreted as Cartesian
coordinates.
\item four columns labelled \code{x,y,seg,tp}
interpreted as Cartesian coordinates and local coordinates.
}
}
}
\value{
A point pattern
on a linear network (object of class \code{"lpp"}).
}
\seealso{
\code{\link{lpp}}.
}
\examples{
A <- as.psp(simplenet)
X <- runifpointOnLines(10, A)
is.ppp(X)
Y <- as.lpp(X, L=simplenet)
}
\author{\adrian
and \rolf
}
\keyword{spatial}
\keyword{math}
\concept{Linear network}
|
