gstat (version 1.0-2)

fit.variogram: Fit a Variogram Model to a Sample Variogram

Description

Fit ranges and/or sills from a simple or nested variogram model to a sample variogram

Usage

fit.variogram(object, model, fit.sills = TRUE, fit.ranges = TRUE,
	fit.method = 7, debug.level = 1, warn.if.neg = FALSE )

Arguments

object

sample variogram, output of variogram

model

variogram model, output of vgm

fit.sills

logical; determines whether the partial sill coefficients (including nugget variance) should be fitted; or logical vector: determines for each partial sill parameter whether it should be fitted or fixed.

fit.ranges

logical; determines whether the range coefficients (excluding that of the nugget component) should be fitted; or logical vector: determines for each range parameter whether it should be fitted or fixed.

fit.method

fitting method, used by gstat. The default method uses weights $N_h/h^2$ with $N_h$ the number of point pairs and $h$ the distance. This criterion is not supported by theory, but by practice. For other values of fit.method, see table 4.2 in

debug.level

integer; set gstat internal debug level

warn.if.neg

logical; if TRUE a warning is issued whenever a sill value of a direct variogram becomes negative

Value

• returns a fitted variogram model (of class variogramModel).

  This is a data.frame has two attributes: (i) singular a logical attribute that indicates whether the non-linear fit converged, or ended in a singularity, and (ii) SSErr a numerical attribute with the (weighted) sum of squared errors of the fitted model. See Notes below.

References

http://www.gstat.org/

Pebesma, E.J., 2004. Multivariable geostatistics in S: the gstat package. Computers & Geosciences, 30: 683-691.

See Also

variogram, vgm

Examples

data(meuse)
vgm1 <- variogram(log(zinc)~1, ~x+y, meuse)
fit.variogram(vgm1, vgm(1,"Sph",300,1))