vario.transfo {RGeostats}R Documentation

Performs transformations between experimental variograms

Description

Performs transformations between experimental variograms

Usage

vario.transfo(string, vario1 = NA, vario2 = NA, vlist = NA, oper=NA)

Arguments

string

Calculation string describing the transformation involving the experimental variograms, for all calculation directions. The user will refer to the variogram contents ("v1" for the first one, "v2" for the second one and so on), to the weight per lag or number of pairs ("w1" for the first one, "w2" for the second one, and so on).

vario1

The vario-class corresponding to the first experimental variogram. It should be refered as "v1" (for the variogram contents, "w1" for the variogram weight) in the calculation string. Note that 'vario1' is used only if 'vlist' is not defined.

vario2

The vario-class corresponding to the second experimental variogram. It should be refered as "v2" (for the variogram contents), "w2" for the variogram weight) in the calculation string. Note that 'vario2' is used only if 'vlist' is not defined.

vlist

An optional list of experimental variograms. This is used when the string involves a large number of experimental variograms (larger than 2). Note that when 'vlist' is used, 'vario1' and 'vario2' are ignored.

oper

Prior transformation to be performed on all variograms involved in the transformation string. It can be one of the following options:

  • g12/g1 Divide the cross-variogram by the first simple variogram

  • g12/g2 Divide the cross-variogram by the second simple variogram

  • g12/sqrt(g1*g2) Divide the cross-variogram by the square root of the product of the two simple variograms

  • norm Normalize each simple variogram by its variance and each cross-variogram by the square root of the product of the variances.

Details

The calculation string must be defined as a string (included within quotes), such as "w1*v1+w2*v2)/(w1+w2)".

Note that the resulting variance array is calculated using the same string, where "v1" stands for the variance of the first variogram and "v2" for the one of the second variogram. In the multivariate case, this is expanded to the array of variance-covariances. For this calculation, the weights "w1" and "w2" are replaced by 1.

No transformation is performed on the distances. The distances are copied from the first variogram ("v1").

As an example, the normalization of a variogram (called "vario") is obtained using the following syntax: vario.transfo("v1",vario1=vario,oper="norm")

Value

The resulting experimental variogram


[Package RGeostats version 11.1.2 Index]