getting values from list of dictionaries using their key

Question

I have a list of dictionaries like below:

What I want to do, is to get the distance value of each element which matches the outer key, which in this case is '500'.

if key == 500: Then print the distance, something like that.

Any help would be appreciated. This is not a duplicate of another post, I tried all the solutions available here, but I failed.

Possible duplicate of [Getting a list of values from a list of dicts](https://stackoverflow.com/questions/7271482/getting-a-list-of-values-from-a-list-of-dicts) — bharatk, Oct 03 '19 at 09:35
@bharatk no, it's not. i already used that but no luck. [d['500'] for d in list_of_dictionary] getting a keyError. or even with [d['distance'] for d in list_of_dictionary] — krunal patel, Oct 03 '19 at 09:38
You should add a code sample that produces some actual output, and a sample of the output that you expected. — Kraay89, Oct 03 '19 at 09:40

Silveris · Answer 1 · 2019-10-03T09:44:19.117

1

Use a simple for loop:

for e in my_list:
    if 500 in e:
        print(e[500]["distance"])

If you are sure the key 500 is present in all dictionaries, it will give you a list of all the distances:

[e[500]['distance'] for e in my_list]

edited Oct 03 '19 at 09:44

answered Oct 03 '19 at 09:36

Silveris

3

It is not redundant... OP didn't tell if the dicts all have the key 500. And no, it will not be true if it is 5000. 500 is an integer, not a string. – Silveris Oct 03 '19 at 09:43
3

@KostasCharitidis it's not redundant. if '500' is not in the dictionairy it will raise a KeyError. Dictionary keys aren't evaluated as a string on a per-key basis, so 500 will never match 5000. – Kraay89 Oct 03 '19 at 09:45
@Silveris Yes, you're right, that solved my query. and stuck in another one if you can help. I have this list list_of_dictionary.append({test_index : {"train_index" : train_index, "distance" : distance, "class" : y_train[train_index-1]}}) what i want is to sort the list according to distance and get the 3 minimum values of a list along with the class attribute. How can i achieve that? – krunal patel Oct 03 '19 at 20:24
@krunalpatel Where is the list? – Silveris Oct 04 '19 at 09:16

score 0 · Answer 2 · answered Oct 03 '19 at 09:53

0

You can simplify this with list comprehension:

def get_distances(list_, key)
    return [obj[key]['distance'] for obj in list_ if key in obj]]

get_distances(list_, 500)

answered Oct 03 '19 at 09:53

Lord Elrond

2 Answers2