nlme: Variogram.default – R documentation

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Variogram.default

Calculate Semi-variogram

Description

This method function calculates the semi-variogram for an arbitrary vector object, according to the distances in distance. For each pair of elements x,y in object, the corresponding semi-variogram is (x-y)^2/2. The semi-variogram is useful for identifying and modeling spatial correlation structures in observations with constant expectation and constant variance.

Usage

## Default S3 method:
Variogram(object, distance, ...)

Arguments

`object`	a numeric vector with the values to be used for calculating the semi-variogram, usually a residual vector from a fitted model.
`distance`	a numeric vector with the pairwise distances corresponding to the elements of `object`. The order of the elements in `distance` must correspond to the pairs `(1,2), (1,3), ..., (n-1,n)`, with `n` representing the length of `object`, and must have length `n(n-1)/2`.
`...`	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 bates@stat.wisc.edu

References

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

Examples

fm1 <- lm(follicles ~ sin(2 * pi * Time) + cos(2 * pi * Time), Ovary,
          subset = Mare == 1)
Variogram(resid(fm1), dist(1:29))[1:10,]

nlme

Linear and Nonlinear Mixed Effects Models

v3.1-152

GPL (>= 2) | file LICENCE

Authors

José Pinheiro [aut] (S version), Douglas Bates [aut] (up to 2007), Saikat DebRoy [ctb] (up to 2002), Deepayan Sarkar [ctb] (up to 2005), EISPACK authors [ctb] (src/rs.f), Siem Heisterkamp [ctb] (Author fixed sigma), Bert Van Willigen [ctb] (Programmer fixed sigma), Johannes Ranke [ctb] (varConstProp()), R-core [aut, cre]

Initial release

2021-02-03