Get all keys of a nested dictionary

Question

I have the below code which currently just prints the values of the initial dictionary. However I would like to iterate through every key of the nested dictionary to initially just print the names. Please see my code below:

Liverpool = {
    'Keepers':{'Loris Karius':1,'Simon Mignolet':2,'Alex Manninger':3},
    'Defenders':{'Nathaniel Clyne':3,'Dejan Lovren':4,'Joel Matip':5,'Alberto Moreno':6,'Ragnar Klavan':7,'Joe Gomez':8,'Mamadou Sakho':9}
}

for k,v in Liverpool.items():
    if k =='Defenders':
       print(v)

Do you want only the deepest key, value pairs to be printed, i.e. the peoples names and their corresponding number or also this key, value pair for example: `'Keepers', {'Loris Karius':1,'Simon Mignolet':2,'Alex Manninger':3}` — timakro, Aug 30 '16 at 17:49
You can use the comprehension list: names = [ name for player in Liverpool.values() for name in player.keys() ] — Monica, Aug 30 '16 at 18:18

score 62 · Answer 1 · answered Aug 30 '16 at 17:58

62

In other answers, you were pointed to how to solve your task for given dicts, with maximum depth level equaling to two. Here is the program that will alows you to loop through key-value pair of a dict with unlimited number of nesting levels (more generic approach):

def recursive_items(dictionary):
    for key, value in dictionary.items():
        if type(value) is dict:
            yield from recursive_items(value)
        else:
            yield (key, value)

a = {'a': {1: {1: 2, 3: 4}, 2: {5: 6}}}

for key, value in recursive_items(a):
    print(key, value)

Prints

1 2
3 4
5 6

That is relevant if you are interested only in key-value pair on deepest level (when value is not dict). If you are also interested in key-value pair where value is dict, make a small edit:

def recursive_items(dictionary):
    for key, value in dictionary.items():
        if type(value) is dict:
            yield (key, value)
            yield from recursive_items(value)
        else:
            yield (key, value)

a = {'a': {1: {1: 2, 3: 4}, 2: {5: 6}}}

for key, value in recursive_items(a):
    print(key, value)

Prints

a {1: {1: 2, 3: 4}, 2: {5: 6}}
1 {1: 2, 3: 4}
1 2
3 4
2 {5: 6}
5 6

answered Aug 30 '16 at 17:58

Dmitry Torba

3,004
1
14
24

1

How would you write this without using `yield from`? Since I'm using Python 2.7. – Sida Zhou Sep 11 '17 at 11:40
3

This doesn't handle the case where the dictionary is inside a list – amirouche Dec 05 '17 at 14:37
1

Like @amirouche mentioned if you have lists inside your dict also add this `if type(value) is list: yield from recursive_items(value[0])` – Yagiz Degirmenci Aug 25 '20 at 20:54
if type(value) is dict and value!={}: handles empty dictionary – VanJeer Oct 04 '21 at 15:56
A more exception-free version to handle lists: `if type(value) is list and len(value) > 0 and type(value[0]) is dict: yield from recursive_items(value[0])` – Manish Jun 21 '22 at 09:41

score 12 · Accepted Answer · edited Aug 14 '18 at 07:14

12

Here is code that would print all team members:

for k, v in Liverpool.items():
    for k1, v1 in v.items():
        print(k1)

So you just iterate every inner dictionary one by one and print values.

edited Aug 14 '18 at 07:14

Shaido

27,497
23
70
73

answered Aug 30 '16 at 17:50

Nikolay Zinov

308
2
7

17

This answer doesn't check whether the inner levels are dictionaries themselves and would result in an error if otherwise. – gented Nov 06 '19 at 15:23

score 1 · Answer 3 · answered Aug 30 '16 at 17:55

Liverpool = {
    'Keepers':{'Loris Karius':1,'Simon Mignolet':2,'Alex Manninger':3},
    'Defenders':{'Nathaniel Clyne':3,'Dejan Lovren':4,'Joel Matip':5,'Alberto Moreno':6,'Ragnar Klavan':7,'Joe Gomez':8,'Mamadou Sakho':9}
}

for k,v in Liverpool.items():
    print(v.keys())

Yields:

['Alberto Moreno', 'Joe Gomez', 'Dejan Lovren', 'Ragnar Klavan', 'Joel Matip', 'Nathaniel Clyne', 'Mamadou Sakho']
['Alex Manninger', 'Loris Karius', 'Simon Mignolet']

Get all keys of a nested dictionary

3 Answers3

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