getGroups {nlme}

Extract Grouping Factors from an Object

Description

This function is generic; method functions can be written to handle specific classes of objects. Classes which already have methods for this function include corStruct, data.frame, gls, lme, lmList, and varFunc.

Usage

getGroups(object, form, level, data, sep)

Arguments

object

any object

form

an optional formula with a conditioning expression on its right hand side (i.e. an expression involving the | operator). Defaults to formula(object).

level

a positive integer vector with the level(s) of grouping to be used when multiple nested levels of grouping are present. This argument is optional for most methods of this generic function and defaults to all levels of nesting.

data

a data frame in which to interpret the variables named in form. Optional for most methods.

sep

character, the separator to use between group levels when multiple levels are collapsed. The default is '/'.

Value

will depend on the method function used; see the appropriate documentation.

Author(s)

José Pinheiro and Douglas Bates [e-mail]

References

Pinheiro, J.C., and Bates, D.M. (2000) "Mixed-Effects Models in S and S-PLUS", Springer, esp. pp. 100, 461.

See Also

getGroupsFormula, getGroups.data.frame, getGroups.gls, getGroups.lmList, getGroups.lme

Examples

## see the method function documentation