To sum up values of same items in a list of tuples while they are string

Question

If I have list of tuples like this:

my_list = [(\'books\', \'$5\'), (\'books\', \'$10\'), (\'ink\', \'$20\'), (\'paper\', \'$15\'), (\'paper\', \'$20\'), (\'pap         


        

Answer 1

This is fairly easy using a dictionary:

result={} #initialize an empty dictionary
for (type,cost) in my_list:
    if type not in result.keys():
        result[type]=int(cost[1:]) #add entry
    else:
        result[type]=result[type]+int(cost[1:]) #increment cost

#make dictionary a list again
dictlist=[]
for key, value in result.iteritems():
    temp = [key,"$"+str(value)] #add dollar sign
    dictlist.append(temp)

print dictlist

Edit: forgot two lines