% $Id: plot.gstatVariogram.Rd,v 1.13 2007-06-08 06:45:51 edzer Exp $
\name{plot.gstatVariogram}
\alias{plot.gstatVariogram}
\alias{plot.variogramMap}
\title{
Plot a Sample Variogram
}
\description{
Creates a variogram plot
}
\usage{
\method{plot}{gstatVariogram}(x, model = NULL, ylim, xlim, xlab = "distance", 
	ylab = "semivariance", panel = vgm.panel.xyplot, multipanel = TRUE, plot.numbers = FALSE, 
	scales, ids = x$id, group.id = TRUE, skip, layout, ...)
\method{plot}{variogramMap}(x, np = FALSE, skip, threshold, ...)
}
\arguments{
\item{x}{ object of class "gstatVariogram", obtained from the function 
\link{variogram}, possibly containing directional or cross variograms }
\item{model}{ in case of a single variogram: a variogram model, as 
obtained from \link{vgm} or \link{fit.variogram}, to be drawn as 
a line in the variogram plot; in case of a set of variograms and
cross variograms: a list with variogram models }
\item{ylim}{ numeric vector of length 2, limits of the y-axis}
\item{xlim}{ numeric vector of length 2, limits of the x-axis}
\item{xlab}{ x-axis label }
\item{ylab}{ y-axis label }
\item{panel}{ panel function }
\item{multipanel}{ logical; if TRUE, directional variograms are plotted in
different panels, if FALSE, directional variograms are plotted in the same
graph, using color, colored lines and symbols to distinguish them }
\item{plot.numbers}{ logical or numeric; if TRUE, plot number of point pairs next to
each plotted semivariance symbol, if FALSE these are omitted. 
If numeric, TRUE is assumed and the value is passed as the relative distance to be used between symbols
and numeric text values (default 0.03). }
\item{scales}{ optional argument that will be passed to \code{xyplot} in
case of the plotting of variograms and cross variograms; use the value
\code{list(relation = "same")} if y-axes need to share scales }
\item{ids}{ ids of the data variables and variable pairs }
\item{group.id}{ logical; control for directional multivariate variograms:
if TRUE, panels divide direction and colors indicate variables
(ids), if FALSE panels divide variables/variable pairs and colors
indicate direction}
\item{skip}{ logical; can be used to arrange panels, see \code{xyplot}}
\item{layout}{ integer vector; can be used to set panel layout: c(ncol,nrow) }
\item{np}{ logical; if TRUE, plot number of point pairs, if FALSE plot
semivariances }
\item{threshold}{semivariogram map values based on fewer point pairs
than threshold will not be plotted}
\item{\dots}{ any arguments that will be passed to the panel plotting functions
(such as \code{auto.key} in examples below) }
}
\value{
returns (or plots) the variogram plot
}
\references{ \url{http://www.gstat.org}}
\author{ Edzer J. Pebesma }
\note{ currently, plotting models and/or point pair numbers is not
supported when a variogram is both directional and multivariable; also,
three-dimensional directional variograms will probably not be displayed
correctly. }
\seealso{
\link{variogram},
\link{fit.variogram}, 
\link{vgm}
\link{variogramLine},
}
\examples{
data(meuse)
coordinates(meuse) = ~x+y
vgm1 <- variogram(log(zinc)~1, meuse)
plot(vgm1)
model.1 <- fit.variogram(vgm1,vgm(1,"Sph",300,1))
plot(vgm1, model=model.1)
plot(vgm1, plot.numbers = TRUE, pch = "+")
vgm2 <- variogram(log(zinc)~1, meuse, alpha=c(0,45,90,135))
plot(vgm2)
# the following demonstrates plotting of directional models:
model.2 <- vgm(.59,"Sph",926,.06,anis=c(0,0.3))
plot(vgm2, model=model.2)
 
g = gstat(NULL, "zinc < 200", I(zinc<200)~1, meuse)
g = gstat(g, "zinc < 400", I(zinc<400)~1, meuse)
g = gstat(g, "zinc < 800", I(zinc<800)~1, meuse)
# calculate multivariable, directional variogram:
v = variogram(g, alpha=c(0,45,90,135))
plot(v, group.id = FALSE, auto.key = TRUE) # id and id pairs panels
plot(v, group.id = TRUE, auto.key = TRUE)  # direction panels

# variogram maps:
plot(variogram(g, cutoff=1000, width=100, map=TRUE),
    main = "(cross) semivariance maps")
plot(variogram(g, cutoff=1000, width=100, map=TRUE), np=TRUE,
    main = "number of point pairs")
}

\keyword{dplot}