Combine items in list

Question

Python3:

dct = {'Mazda': [['Ford', 95], ['Toyota', 20], ['Chrysler', 52], ['Toyota', 5], ['Toyota', 26]]}

I have the above dictionary with the values being a list within a list. What I would like to do is combine the items within the list that are the same and add the integer to that value.

eg. since Toyota is in there 3x then combine all the numbers together to give me another list

[Toyota, 51]

Final result should be does not need to be in this order

dct = {'Mazda': [['Ford', 95], ['Toyota', 51], ['Chrysler', 52]]}

Answer 1

For the input in the question:

dct = {'Mazda': [['Ford', 95],  ['Toyota', 20], ['Chrysler', 52],
                 ['Toyota', 5], ['Toyota', 26]]}

Try this:

from collections import defaultdict

for k, v in dct.items():
    aux = defaultdict(int)
    for car, num in v:
        aux[car] += num
    dct[k] = map(list, aux.items())

Now dct contains the expected result:

dct
=> {'Mazda': [['Ford', 95], ['Toyota', 51], ['Chrysler', 52]]}