nlme (version 3.1-1)

getGroups.corStruct: Extract corStruct Groups

Description

This method function extracts the grouping factor associated with object, if any is present.

Usage

getGroups(object, form, data, level)

Arguments

object

an object inheriting from class corStruct representing a correlation structure.

form

this argument is included to make the method function compatible with the generic. It will be assigned the value of formula(object) and should not be modified.

data

an optional data frame in which to evaluate the variables defined in form, in case object is not initialized and the grouping factor needs to be evaluated.

level

this argument is included to make the method function compatible with the generic and is not used.

Value

• if a grouping factor is present in the correlation structure represented by object, the function returns the corresponding factor vector; else the function returns NULL.

See Also

getGroups

Examples

data(Orthodont)
cs1 <- corAR1(form = ~ 1 | Subject)
getGroups(cs1, data = Orthodont)