formula.ppm.Rd
\name{formula.ppm}
\alias{formula.ppm}
\alias{terms.ppm}
\title{
Model Formulae for Gibbs Point Process Models
}
\description{
Extract the trend formula, or the terms in the trend formula,
in a fitted Gibbs point process model.
}
\usage{
\method{formula}{ppm}(x, \dots)
\method{terms}{ppm}(x, \dots)
}
\arguments{
\item{x}{
An object of class \code{"ppm"},
representing a fitted point process model.
}
\item{\dots}{
Arguments passed to other methods.
}
}
\details{
These functions are methods for the generic commands
\code{\link{formula}} and
\code{\link{terms}}
for the class \code{"ppm"}.
An object of class \code{"ppm"} represents a fitted
Poisson or Gibbs point process model.
It is obtained from the model-fitting function \code{\link{ppm}}.
The method \code{formula.ppm} extracts the trend formula from the
fitted model \code{x} (the formula originally specified as the
argument \code{trend} to \code{\link{ppm}}).
The method \code{terms.ppm} extracts the individual
terms in the trend formula.
}
\value{
See the help files for the corresponding generic functions.
}
\author{
\adrian
}
\seealso{
\code{\link{ppm}},
\code{\link{as.owin}},
\code{\link{coef.ppm}},
\code{\link{extractAIC.ppm}},
\code{\link{fitted.ppm}},
\code{\link{logLik.ppm}},
\code{\link{model.frame.ppm}},
\code{\link{model.matrix.ppm}},
\code{\link{plot.ppm}},
\code{\link{predict.ppm}},
\code{\link{residuals.ppm}},
\code{\link{simulate.ppm}},
\code{\link{summary.ppm}},
\code{\link{update.ppm}},
\code{\link{vcov.ppm}}.
}
\examples{
data(cells)
fit <- ppm(cells, ~x)
formula(fit)
terms(fit)
}
\keyword{spatial}
\keyword{methods}