code: def select_grid_model_residential(lvgd):
      
  
      # Load properties of LV typified model grids
      string_properties = lvgd.lv_grid.network.static_data['LV_model_grids_strings']
      # Load relational table of apartment count and strings of model grid
      apartment_string = lvgd.lv_grid.network.static_data[
          'LV_model_grids_strings_per_grid']
  
      # load assumtions
      apartment_house_branch_ratio = cfg_ding0.get("assumptions",
                                                   "apartment_house_branch_ratio")
      population_per_apartment = cfg_ding0.get("assumptions",
                                               "population_per_apartment")
  
      # calc count of apartments to select string types
      apartments = round(lvgd.population / population_per_apartment)
  
      if apartments > 196:
          apartments = 196
  
      # select set of strings that represent one type of model grid
      strings = apartment_string.loc[apartments]
      selected_strings = [int(s) for s in strings[strings >= 1].index.tolist()]
  
      # slice dataframe of string parameters
      selected_strings_df = string_properties.loc[selected_strings]
  
      # add number of occurences of each branch to df
      occurence_selector = [str(i) for i in selected_strings]
      selected_strings_df['occurence'] = strings.loc[occurence_selector].tolist()
  
      return selected_strings_df
docs: Selects typified model grid based on population
  
      Parameters
      ----------
      lvgd : LVGridDistrictDing0
          Low-voltage grid district object
  
      Returns
      -------
      :pandas:`pandas.DataFrame<dataframe>`
          Selected string of typified model grid
      :pandas:`pandas.DataFrame<dataframe>`
          Parameters of chosen Transformer
  
      Notes
      -----
      In total 196 distinct LV grid topologies are available that are chosen
      by population in the LV grid district. Population is translated to
      number of house branches. Each grid model fits a number of house
      branches. If this number exceeds 196, still the grid topology of 196
      house branches is used. The peak load of the LV grid district is
      uniformly distributed across house branches.