grouping

itertools.groupby can do what you want: import itertools import operator L = [(‘grape’, 100), (‘grape’, 3), (‘apple’, 15), (‘apple’, 10), (‘apple’, 4), (‘banana’, 3)] def accumulate(l): it = itertools.groupby(l, operator.itemgetter(0)) for key, subiter in it: yield key, sum(item[1] for item in subiter) print(list(accumulate(L))) # [(‘grape’, 103), (‘apple’, 29), (‘banana’, 3)]