code: def results(self, Pc):
          r
          Psatn = self['pore.invasion_pressure'] <= Pc
          Tsatn = self['throat.invasion_pressure'] <= Pc
          inv_phase = {}
          inv_phase['pore.occupancy'] = sp.array(Psatn, dtype=float)
          inv_phase['throat.occupancy'] = sp.array(Tsatn, dtype=float)
          return inv_phase