Variogram.corSpher Calculate Semi-variogram for a corSpher Object

Description

This method function calculates the semi-variogram values corresponding to the Spherical correlation model, using the estimated coefficients corresponding to object, at the distances defined by distance.

Usage

## S3 method for class 'corSpher'
Variogram(object, distance, sig2, length.out, ...)

Arguments

object	an object inheriting from class "corSpher", representing an Spherical spatial correlation structure.
distance	an optional numeric vector with the distances at which the semi-variogram is to be calculated. Defaults to NULL, in which case a sequence of length length.out between the minimum and maximum values of getCovariate(object) is used.
sig2	an optional numeric value representing the process variance. Defaults to 1.
length.out	an optional integer specifying the length of the sequence of distances to be used for calculating the semi-variogram, when distance = NULL. Defaults to 50.
...	some methods for this generic require additional arguments. None are used in this method.

Value

a data frame with columns variog and dist representing, respectively, the semi-variogram values and the corresponding distances. The returned value inherits from class Variogram.

Author(s)

José Pinheiro and Douglas Bates [email protected]

References

Cressie, N.A.C. (1993), "Statistics for Spatial Data", J. Wiley & Sons.

See Also

corSpher, plot.Variogram, Variogram

Examples

cs1 <- corSpher(15, form = ~ Time | Rat)
cs1 <- Initialize(cs1, BodyWeight)
Variogram(cs1)[1:10,]