import IMP.example import IMP.core import IMP.container bb= IMP.algebra.BoundingBox3D(IMP.algebra.Vector3D(0,0,0), IMP.algebra.Vector3D(10,10,10)) m= IMP.Model() ps= IMP.core.create_xyzr_particles(m, 20, 1) sc= IMP.container.ListSingletonContainer(ps) ss= IMP.container.SingletonsConstraint(sc, IMP.example.ExampleSingletonModifier(bb), None) m.add_score_state(ss) # now optimize and things