Sum numbers by letter in list of tuples

Question

I have a list of tuples:

[ (\'A\',100), (\'B\',50), (\'A\',50), (\'B\',20), (\'C\',10) ]

I am trying to sum up all numbers that have the s

Answer 1

A one liner:

>>> x = [ ('A',100), ('B',50), ('A',50), ('B',20), ('C',10) ]
>>> {
...     k: reduce(lambda u, v: u + v, [y[1] for y in x if y[0] == k])
...     for k in [y[0] for y in x]
...     }.items()
[('A', 150), ('C', 10), ('B', 70)]