getCovariate.varFunc function

Extract varFunc Covariate

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

## S3 method for class 'varFunc'
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.

Returns

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

Author(s)

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

See Also

covariate<-.varFunc

Examples

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