how to identify highest value key in nested dictionary?

Question

As a python newbie, I have a dictionary d:

d={'a':{'1':4,'2':6},'b':{'1':5,'2':10}}

I need to find for each key ('a','b') the sub-key for the highest value and bundle them together in a new dictionary, newd, which looks like

newd={'a':'2', 'b':'2'}

what is the best way to achieve this?

What should this do if two keys have the highest value, like `{'a': {'1': 4, '2': 4}}`? Pick one arbitrarily? — abarnert, May 04 '18 at 21:27

Ajax1234 · Answer 1 · 2018-05-04T21:10:38.640

10

You can use a dictionary comprehension with max:

d={'a':{'1':4,'2':6},'b':{'1':5,'2':10}}
new_d = {a:max(b, key=b.get) for a, b in d.items()}

Output:

{'a': '2', 'b': '2'}

edited May 04 '18 at 21:10

answered May 04 '18 at 21:07

Ajax1234

69,937
8
61
102

Daniele Cappuccio · Answer 2 · 2018-05-04T21:18:48.150

2

d = {'a': {'1':4,'2':6},'b': {'1':5,'2':10}}

newd = {}
for key, value in d.items():
    max_value = max([i for i in value.values()])
    for k in value:
            if value[k] == max_value:
                    newd[key] = k

print(newd)
# prints '{'a': '2', 'b': '2'}'

edited May 04 '18 at 21:18

answered May 04 '18 at 21:08

Daniele Cappuccio

1,952
2
16
31

It looks like the OP wants the key corresponding to the highest value, not the key that's highest in itself. – abarnert May 04 '18 at 21:10
Mmm ok I misunderstood, I'll edit my answer – Daniele Cappuccio May 04 '18 at 21:11
now it should be fine. tho idk what the op wants when there's more than one key corresponding to the highest value. – Daniele Cappuccio May 04 '18 at 21:23
That's a good question. – abarnert May 04 '18 at 21:26

score 1 · Answer 3 · answered May 04 '18 at 22:08

1

new_dict = {}
for k, v in d.items():
    new_dict[k] = max(v.values())

answered May 04 '18 at 22:08

suri

171
1
1
6

how to identify highest value key in nested dictionary?

3 Answers3