R: Extract Grouping Formula

Extract Grouping Formula

Usage

getGroupsFormula(object, asList)

Arguments

`object`	any object from which a formula can be extracted.
`asList`	an optional logical value. If `TRUE` the returned value with be a list of formulas; else, if `FALSE` the returned value will be a one-sided formula. Defaults to `FALSE`.

Description

The conditioning expression associated with formula(object) (i.e. an expression after a | operator) is returned either as a named list of one-sided formulas, or a single one-sided formula, depending on the value of asList. The components of the returned list are ordered from outermost to innermost level and are named after the grouping factor expression.

Value

a one-sided formula, or a list of one-sided formulas, with the grouping structure associated with formula(object). If no conditioning expression is present in formula(object) a NULL value is returned.

Author(s)

Jose Pinheiro and Douglas Bates

Examples

library(lme)
getGroupsFormula(y ~ x | g1/g2)

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