lpp.Rd
\name{lpp}
\alias{lpp}
\title{
Create Point Pattern on Linear Network
}
\description{
Creates an object of class \code{"lpp"} that represents
a point pattern on a linear network.
}
\usage{
lpp(X, L, \dots)
}
\arguments{
\item{X}{
Locations of the points. A matrix or data frame of coordinates,
or a point pattern object (of class
\code{"ppp"}) or other data acceptable to \code{\link{as.ppp}}.
}
\item{L}{
Linear network (object of class \code{"linnet"}).
}
\item{\dots}{
Ignored.
}
}
\details{
This command creates an object of class \code{"lpp"} that represents
a point pattern on a linear network.
Normally \code{X} is a point pattern. The points of \code{X} should lie
on the lines of \code{L}.
Alternatively \code{X} may be a matrix or data frame containing at
least two columns.
\itemize{
\item Usually
the first two columns of \code{X} will be interpreted
as spatial coordinates, and any remaining columns as marks.
\item
An exception occurs if \code{X} is a data frame with columns named
\code{x}, \code{y}, \code{seg} and \code{tp}. Then
\code{x} and \code{y} will be interpreted as spatial
coordinates, and \code{seg} and \code{tp} as local
coordinates, with \code{seg} indicating which line segment of
\code{L} the point lies on, and \code{tp} indicating how far along
the segment the point lies (normalised to 1). Any remaining columns
will be interpreted as marks.
\item
Another exception occurs if \code{X} is a data frame with columns named
\code{seg} and \code{tp}. Then
\code{seg} and \code{tp} will be interpreted as local
coordinates, as above, and the spatial coordinates
\code{x,y} will be computed from them.
Any remaining columns will be interpreted as marks.
}
}
\section{Note on changed format}{
The internal format of \code{"lpp"} objects was changed in
\pkg{spatstat} version \code{1.28-0}.
Objects in the old format are still handled correctly,
but computations are faster in the new format.
To convert an object \code{X} from the old format to the new format,
use \code{X <- lpp(as.ppp(X), as.linnet(X))}.
}
\value{
An object of class \code{"lpp"}.
Also inherits the class \code{"ppx"}.
}
\author{
Ang Qi Wei \email{aqw07398@hotmail.com} and
\adrian
}
\seealso{
Installed datasets which are \code{"lpp"} objects:
\code{\link{chicago}}, \code{\link{dendrite}}, \code{\link{spiders}}.
See \code{\link{as.lpp}} for converting data to an \code{lpp} object.
See \code{\link{methods.lpp}} and
\code{\link{methods.ppx}} for other methods applicable
to \code{lpp} objects.
Calculations on an \code{lpp} object:
\code{\link{intensity.lpp}},
\code{\link{distfun.lpp}},
\code{\link{nndist.lpp}},
\code{\link{nnwhich.lpp}},
\code{\link{nncross.lpp}},
\code{\link{nnfun.lpp}}.
Summary functions:
\code{\link{linearK}},
\code{\link{linearKinhom}},
\code{\link{linearpcf}},
\code{\link{linearKdot}},
\code{\link{linearKcross}},
\code{\link{linearmarkconnect}}, etc.
Random point patterns on a linear network can be generated by
\code{\link{rpoislpp}} or \code{\link{runiflpp}}.
See \code{\link{linnet}} for linear networks.
}
\examples{
# letter 'A'
v <- ppp(x=(-2):2, y=3*c(0,1,2,1,0), c(-3,3), c(-1,7))
edg <- cbind(1:4, 2:5)
edg <- rbind(edg, c(2,4))
letterA <- linnet(v, edges=edg)
# points on letter A
xx <- list(x=c(-1.5,0,0.5,1.5), y=c(1.5,3,4.5,1.5))
X <- lpp(xx, letterA)
plot(X)
X
summary(X)
}
\keyword{spatial}