Sort a dictionary by values in a nested dictionary

Question

I have dictionary like so:

   dic = {first_a : { first_b : {10, 2} } , second_a : {second_b : {13, 15} } [...] }

I would like to sort the nested dictionary according to the sum of x_a and y_a. I can't get my head around this one, could someone provide an helping hand ? I have tried to use the sorted() function but wasn't able to find the right lambda function to use as key..

Answer 1

Assuming that you meant to have a dictionary like this:

data = {'a': {'b': {2, 10}}, 'c': {'d': {13, 15}}}

You can get what you want like this:

sorted(data, key =lambda k: sum(*dic[k].values()), reverse=True)

However I don't consider this very readable. I would instead do:

def get_sum(k):
    vals, *_ = data[k].values()
    return sum(vals)

sorted(data, key=get_sum, reverse=True)

When I'm looking at code late at night, too many parentheses == too long to figure out what's happening.

Note that I used values() because I didn't know if your inner keys were constant. If they were, life is even easier. Note this operates on and sorts the keys .