code: def _create_ids(self, home_teams, away_teams):
          
          categories = pd.Categorical(np.append(home_teams,away_teams))
          home_id, away_id = categories.codes[0:int(len(categories)/2)], categories.codes[int(len(categories)/2):len(categories)+1]
          return home_id, away_id
docs: Creates IDs for both players/teams