Question

For python In this chapter, we implemented the Set ADT using a list. Implement the Set ADT using a bag created from the Bag class. In your opinion, which is the better implementation? Explain your answer.

Answer 1

from collections import defaultdict
from goody import type_as_str
import copy
from collections import Counter

class Bag:

     def __init__(self, items = []):
         self.bag_value = defaultdict(int)
         for item in items:
             self.bag_value[item] += 1


     def __repr__(self):
         bag_list = []
         for item, count in self.bag_value.items():
             bag_list.extend(list(item*count))
         return 'Bag(' + str(bag_list) + ')'



     def __str__(self):
         return 'Bag(' + ','.join(str(item) + '[' + str(count) + ']' for item, count in self.bag_value.items()) + ')'



     def __len__(self):
         bag_len = 0
         for value in self.bag_value:
             bag_len += self.bag_value[value]
         return bag_len



     def unique(self):
         return len(self.bag_value)




      def __contains__(self, item):
          return item in self.bag_value



      def count(self, item):
          if item in self.bag_value:
             return self.bag_value[item]
          else:
             return 0



      def add(self, new):
          self.bag_value[new] += 1



      def __add__(self,right):
          mergedbag = Bag()
          mergedbag.bag_value = copy.copy(self.bag_value)
          for item in right.bag_value.keys():
              mergedbag.bag_value[item] += right.bag_value[item]
          return mergedbag



      def remove(self, item):
          if item in self.bag_value:
              if self.bag_value[item] == 1:
                  del self.bag_value[item]
              else:
                  self.bag_value[item] -= 1
          else:
              raise ValueError(str(item) + ' not in bag')



      def __eq__(self, right):
          if type(right) is not Bag:
              raise TypeError('Cannot compare Bag with' + type_as_str(right) + '. Can only compare Bag with Bag')
          else:
              return (Counter(self.bag_value)==Counter(right))



      def __ne__(self, right):
          return not self.__eq__(right)



      def __generate__(self, bag_value):
          for item in self.bag_value:
              for value in range(self.bag_value[item]):
                  yield item



      def __iter__(self):
          return self.__generate__(self.bag_value)




if __name__ == '__main__':
#     bag = Bag(['d','a','b','d','c','b','d'])
#     bag2 = Bag(['d','a','b','d','c','b','d'])
#     bag3 = Bag(['d','a','b','d','c','b'])
#     print(bag == bag2)
#     print(bag == bag3)
#     print(bag != bag2)
#     print(bag != bag3)
    import driver
    driver.driver()