Extract components from a formula with "conditioning bar"
Description
Extract components from a formula with the form y~x1+...xng1+...gm
Usage
1  parseGroupFormula(form)

Arguments
form 
A formula of the form 
Value
If the formula is y~x1+x2g1+g2
the result is
model 

groups 

groupFormula 

Note
This function is a recent addition and has not been thoroughly tested. Please report bugs.
Author(s)
S<f8>ren H<f8>jsgaard, sorenh@math.aau.dk
Examples
1  gf<parseGroupFormula(y~x1+x2g1+g2)
