knapsack using greedy algorithm

#knapsack problem using greedy method 
class Sack:
    def __init__(self,weight,profit,index):
        self.weight=weight
        self.profit=profit
        self.index=index
        self.profitperkg=profit//weight

    def __lt__(self,other):
        return self.profitperkg<other.profitperkg

class knapsack:
    
      def appendingvalue(self,weight,profit,capacity):


          value=[]

          for i in range(len(weight)):
               value.append(Sack(weight[i],profit[i],i))
          value.sort(reverse=True)


       
          total_value=0
          for position in value:
              currentweight=int(position.weight)
              currentprofit=int(position.profit)
              if capacity-currentweight>=0:
                  capacity -=currentweight
                  total_value +=currentprofit
              else:
                  fraction=capacity/currentweight
                  total_value+=fraction*currentprofit
                  capacity-=int(fraction*currentweight)
                  
                  break
          return total_value