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 use defaultdict to do this:

>>> from collections import defaultdict
>>> my_list = [('books', '$5'), ('books', '$10'), ('ink', '$20'), ('paper', '$15'), ('paper', '$20'), ('paper', '$15')] 
>>> res = defaultdict(list)
>>> for item, price in my_list:
...     res[item].append(int(price.strip('$')))
... 
>>> total = [(k, "${}".format(sum(v))) for k, v in res.items()]
>>> total
[('ink', '$20'), ('books', '$15'), ('paper', '$50')]