code: def get_sigmoid_parameters(self, filename='shlp_sigmoid_factors.csv'):
          
  
          file = os.path.join(self.datapath, filename)
          sigmoid = pd.read_csv(file, index_col=0)
          sigmoid = sigmoid.query(
              'building_class=={0} and '.format(self.building_class) +
              'shlp_type=="{0}" and '.format(self.shlp_type) +
              'wind_impact=={0}'.format(self.wind_class))
  
          a = float(sigmoid['parameter_a'])
          b = float(sigmoid['parameter_b'])
          c = float(sigmoid['parameter_c'])
          if self.ww_incl:
              d = float(sigmoid['parameter_d'])
          else:
              d = 0
          return a, b, c, d
docs: Retrieve the sigmoid parameters from csv-files
  
          Parameters
          ----------
          filename : string
              name of file where sigmoid factors are stored