code: def write_bus_data(self, file):
          
  #        labels = ["bus_id", "type", "Pd", "Qd", "Gs", "Bs", "area", "Vm", "Va",
  #            "baseKV", "Vmax", "Vmin"]
  
          bus_attrs = ["_i", "type", "p_demand", "q_demand", "g_shunt","b_shunt",
              "area", "v_magnitude", "v_angle", "v_base", "zone",
              "v_max", "v_min", "p_lmbda", "q_lmbda", "mu_vmin", "mu_vmax"]
  
          file.write("\n%%%% bus data\n")
          file.write("%%\tbus_i\ttype\tPd\tQd\tGs\tBs\tarea\tVm\tVa\tbaseKV"
                     "\tzone\tVmax\tVmin\tlam_P\tlam_Q\tmu_Vmax\tmu_Vmin")
          file.write("\n%sbus = [\n" % self._prefix)
  
  
          for bus in self.case.buses:
              vals = [getattr(bus, a) for a in bus_attrs]
              d = {PQ: 1, PV: 2, REFERENCE: 3, ISOLATED: 4}
              vals[1] = d[vals[1]]
  
              assert len(vals) == 17
  
              file.write("\t%d\t%d\t%g\t%g\t%g\t%g\t%d\t%.8g\t%.8g\t%g\t%d\t%g"
                         "\t%g\t%.4f\t%.4f\t%.4f\t%.4f;\n" % tuple(vals[:]))
          file.write("];\n")
docs: Writes bus data in MATPOWER format.