fitted.ppm.Rd
\name{fitted.ppm}
\alias{fitted.ppm}
\title{
Fitted Conditional Intensity for Point Process Model
}
\description{
Given a point process model fitted to a point pattern,
compute the fitted conditional intensity of the model
at the points of the pattern,
or at the points of the quadrature scheme used to fit the model.
}
\usage{
\method{fitted}{ppm}(object, \dots, type="lambda", dataonly=FALSE,
check=TRUE, repair=TRUE)
}
\arguments{
\item{object}{
The fitted point process model (an object of class \code{"ppm"})
}
\item{\dots}{
Ignored.
}
\item{type}{
String (partially matched) indicating whether the fitted value is the
conditional intensity (\code{"lambda"}) or the trend
(\code{"trend"}).
}
\item{dataonly}{
Logical. If \code{TRUE}, then values will only be computed
at the points of the data point pattern. If \code{FALSE}, then
values will be computed at all the points of the quadrature scheme
used to fit the model, including the points of the data point pattern.
}
\item{check}{
Logical value indicating whether to check the internal format
of \code{object}. If there is any possibility that this object
has been restored from a dump file, or has otherwise lost track of
the environment where it was originally computed, set
\code{check=TRUE}.
}
\item{repair}{
Logical value indicating whether to repair the internal format
of \code{object}, if it is found to be damaged.
}
}
\value{
A vector containing the values of the fitted conditional intensity
or (if \code{type="trend"}) the fitted spatial trend.
Entries in this vector correspond to the quadrature points (data or
dummy points) used to fit the model. The quadrature points can be
extracted from \code{object} by \code{union.quad(quad.ppm(object))}.
}
\details{
The argument \code{object} must be a fitted point process model
(object of class \code{"ppm"}). Such objects are produced by the
model-fitting algorithm \code{\link{ppm}}).
This function evaluates the conditional intensity
\eqn{\hat\lambda(u, x)}{lambdahat(u,x)}
or spatial trend \eqn{\hat b(u)}{bhat(u)} of the fitted point process
model for certain locations \eqn{u},
where \code{x} is the original point pattern dataset to which
the model was fitted.
The locations \eqn{u} at which the fitted conditional intensity/trend
is evaluated, are the points of the
quadrature scheme used to fit the model in \code{\link{ppm}}.
They include the data points (the points of the original point pattern
dataset \code{x}) and other ``dummy'' points
in the window of observation.
Use \code{\link{predict.ppm}} to compute the fitted conditional
intensity at other locations or with other values of the
explanatory variables.
}
\references{
Baddeley, A., Turner, R., Moller, J. and Hazelton, M. (2005).
Residual analysis for spatial point processes (with discussion).
\emph{Journal of the Royal Statistical Society, Series B}
\bold{67}, 617--666.
}
\seealso{
\code{\link{ppm.object}},
\code{\link{ppm}},
\code{\link{predict.ppm}}
}
\examples{
data(cells)
str <- ppm(cells, ~x, Strauss(r=0.15))
lambda <- fitted(str)
# extract quadrature points in corresponding order
quadpoints <- union.quad(quad.ppm(str))
# plot conditional intensity values
# as circles centred on the quadrature points
quadmarked <- setmarks(quadpoints, lambda)
plot(quadmarked)
}
\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{methods}
\keyword{models}