nlme (version 3.1-130)

getCovariate.varFunc: Extract varFunc Covariate

Description

This method function extracts the covariate(s) associated with the variance function represented by object, if any is present.

Usage

"getCovariate"(object, form, data)

Arguments

object

an object inheriting from class varFunc, representing a variance function structure.

form

an optional formula specifying the covariate to be evaluated in object. Defaults to formula(object).

data

some methods for this generic require a data object. Not used in this method.

Value

if object has a covariate attribute, its value is returned; else NULL is returned.

See Also

covariate<-.varFunc

Examples

vf1 <- varPower(1.1, form = ~age)
covariate(vf1) <- Orthodont[["age"]]
getCovariate(vf1)