Calculate Semi-variogram for a corGaus Object

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

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

Arguments

object: an object inheriting from class "corGaus", representing an Gaussian 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.

References

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

Author

José Pinheiro and Douglas Bates bates@stat.wisc.edu

Examples

cs1 <- corGaus(3, form = ~ Time | Rat)
cs1 <- Initialize(cs1, BodyWeight)
Variogram(cs1)[1:10,]
#>       variog      dist
#> 1  0.1051607  1.000000
#> 2  0.4345758  2.265306
#> 3  0.7496824  3.530612
#> 4  0.9223581  4.795918
#> 5  0.9831271  6.061224
#> 6  0.9974310  7.326531
#> 7  0.9997259  8.591837
#> 8  0.9999795  9.857143
#> 9  0.9999989 11.122449
#> 10 1.0000000 12.387755