Extract Grouping Formula

DESCRIPTION:

The conditioning expression associated with formula(object) (i.e. an expression after the `|' 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.

USAGE:

getGroupsFormula(object, asList) 

REQUIRED ARGUMENTS:

object
any object from which a formula can be extracted.

OPTIONAL ARGUMENTS:

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.

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.

SEE ALSO:

, , , ,

EXAMPLES:

getGroupsFormula(y ~ x | g1/g2)