https://github.com/cran/spatstat
Tip revision: c75a36fce807d4a1105403c1f8628a196a3e54da authored by Adrian Baddeley on 24 October 2008, 14:28:47 UTC
version 1.14-5
version 1.14-5
Tip revision: c75a36f
rstrat.Rd
\name{rstrat}
\alias{rstrat}
\title{Simulate Stratified Random Point Pattern}
\description{
Generates a ``stratified random'' pattern of points in a window,
by dividing the window into rectangular tiles and placing
\code{k} random points independently in each tile.
}
\usage{
rstrat(win=square(1), nx, ny=nx, k = 1)
}
\arguments{
\item{win}{
A window.
An object of class \code{\link{owin}},
or data in any format acceptable to \code{\link{as.owin}()}.
}
\item{nx}{Number of tiles in each column.
}
\item{ny}{Number of tiles in each row.
}
\item{k}{Number of random points to generate in each tile.
}
}
\value{
A point pattern (object of class \code{"ppp"}).
}
\details{
This function generates a random pattern of points
in a ``stratified random'' sampling design. It can be useful
for generating random spatial sampling points.
The bounding rectangle of \code{win} is divided into
a regular \eqn{nx \times ny}{nx * ny} grid of rectangular tiles.
In each tile, \code{k} random points are generated independently
with a uniform distribution in that tile.
Some of these grid points may lie outside the window \code{win}:
if they do, they are deleted.
The result is a point pattern inside the window \code{win}.
This function is useful in creating dummy points for quadrature
schemes (see \code{\link{quadscheme}}) as well as in simulating
random point patterns.
}
\seealso{
\code{\link{rsyst}},
\code{\link{runifpoint}},
\code{\link{quadscheme}}
}
\examples{
X <- rstrat(nx=10)
plot(X)
# polygonal boundary
data(letterR)
X <- rstrat(letterR, 5, 10, k=3)
plot(X)
}
\author{Adrian Baddeley
\email{adrian@maths.uwa.edu.au}
\url{http://www.maths.uwa.edu.au/~adrian/}
and Rolf Turner
\email{r.turner@auckland.ac.nz}
}
\keyword{spatial}
\keyword{datagen}