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% File nlme/man/Variogram.corSpatial.Rd
% Part of the nlme package for R
% Distributed under GPL 2 or later: see nlme/LICENCE
% $Id: Variogram.corSpatial.Rd,v 1.7.2.2 2003/04/17 22:28:45 bates Exp $
\name{Variogram.corSpatial}
\title{Calculate Semi-variogram for a corSpatial Object}
\usage{
\method{Variogram}{corSpatial}(object, distance, sig2, length.out, FUN, \dots)
}
\alias{Variogram.corSpatial}
\arguments{
\item{object}{an object inheriting from class \code{corSpatial},
representing spatial correlation structure.}
\item{distance}{an optional numeric vector with the distances at
which the semi-variogram is to be calculated. Defaults to
\code{NULL}, in which case a sequence of length \code{length.out}
between the minimum and maximum values of
\code{getCovariate(object)} is used.}
\item{sig2}{an optional numeric value representing the process
variance. Defaults to \code{1}.}
\item{length.out}{an optional integer specifying the length of the
sequence of distances to be used for calculating the semi-variogram,
when \code{distance = NULL}. Defaults to \code{50}.}
\item{FUN}{a function of two arguments, the distance and the range
corresponding to \code{object}, specifying the semi-variogram
model.}
\item{\dots}{some methods for this generic require additional
arguments. None are used in this method.}
}
\description{
This method function calculates the semi-variogram values
corresponding to the model defined in \code{FUN}, using the estimated
coefficients corresponding to \code{object}, at the distances defined
by \code{distance}.
}
\value{
a data frame with columns \code{variog} and \code{dist} representing,
respectively, the semi-variogram values and the corresponding
distances. The returned value inherits from class \code{Variogram}.
}
\references{
Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.
}
\author{Jose Pinheiro \email{Jose.Pinheiro@pharma.novartis.com} and Douglas Bates \email{bates@stat.wisc.edu}}
\seealso{
\code{\link{corSpatial}},
\code{\link{Variogram}},
\code{\link{Variogram.default}},
\code{\link{Variogram.corExp}},
\code{\link{Variogram.corGaus}},
\code{\link{Variogram.corLin}},
\code{\link{Variogram.corRatio}},
\code{\link{Variogram.corSpher}},
\code{\link{plot.Variogram}}
}
\examples{
cs1 <- corExp(3, form = ~ Time | Rat)
cs1 <- Initialize(cs1, BodyWeight)
Variogram(cs1, FUN = function(x, y) (1 - exp(-x/y)))[1:10,]
}
\keyword{models}
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