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

You can simply use a dictionary to solve this problem.

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

sums = {}
for item, price in my_list:
    sums[item] = sums.get(item, 0) + int(price[1:])

print sums

And if you need list of tuples, just do

print sums.items()

And to get your the output you expect,

print [(item, '$' + str(price)) for item, price in sums.items()]

Update

If you have costs with floating point value, you can simply change int to float like this and rest of the code remains the same,

sums[item] = sums.get(item, 0) + float(price[1:])