Code:
#easy way
target = viz.addGroup(pos=[1,0,1])
root = viz.addGroup(pos=[6,1,3])
helper = viz.addGroup(parent=root)
helper.setPosition(target.getPosition(), viz.ABS_GLOBAL)
print helper.getPosition() #mode defaults to viz.ABS_PARENT
#mathy way
#T=OR so T(1/R)=0
T = target.getMatrix()
R = root.getMatrix()
O = T * R.inverse()
print O.getTrans()