I have a nested list that looks like this:
nested = [['a', 1], ['v', 2], ['a', 5], ['v', 3]]
I want to sum values in nested list for each letter value in list, so that output looks like this:
[['a', 6], ['v', 5]]
I have tried to play with for loops, but I couldnt find the solution.
There is probably a one liner for this using reduce and list comp, but I couldn't see it quickly.
nested = [['a', 1], ['v', 2], ['a', 5], ['v', 3]]
from collections import defaultdict
d = defaultdict(int)
for i in nested:
d[i[0]] += i[1]
retval = []
for k, v in d.items():
retval.append([k, v])
print(retval) # [['a', 6], ['v', 5]]
