Concatenate nested same key values in sub objects in python dictionary

Question

I have this python dictionary that contains inside some nested objects:

Input

 {
            "data": [
                {
                    "name": "default",
                    "type": "pkg"
                },
                {
                    "name": "name1",
                    "subobj": [
                        {
                            "name": "subname1",
                            "subobj": [
                                {
                                    "name": "sub-subname1",
                                    "type": "pkg"
                                },
                                {
                                    "name": "sub-subname2",
                                    "type": "pkg"
                                }
                            ],
                            "type": "folder"
                        }
                    ],
                    "type": "folder"
                }
            ]
}

I need to recursively create a list that concatenates the "name" keys (maintaining the hierarchy) like the following:

Output

default
name1/subname1/sub-subname1
name1/subname1/sub-subname2

How Could I achieve this Output taking in consideration that could be there infinite nested object in subobj ?

tobias_k · Accepted Answer · 2022-09-15 16:36:05Z

3

You can do this with a rather simple recursive function, building up a prefix string of parent names and finally yielding the combined names for all the pkg items.

def get_names(lst, prefix=""):
    for d in lst:
        if d["type"] == "pkg":
            yield f"{prefix}{d['name']}"
        elif d["type"] == "folder":
            yield from get_names(d["subobj"], f"{prefix}{d['name']}/")

Then call this for the data["data"] item (data being your full nested dictionary):

for name in get_names(data["data"]):
    print(name)

Output:

default
name1/subname1/sub-subname1
name1/subname1/sub-subname2

edited Sep 15, 2022 at 16:36

answered Sep 15, 2022 at 16:30

tobias_k

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Comments

Lucas M. Uriarte · Accepted Answer · 2022-09-15 17:24:06Z

1

I think this function should make the job

from typing import Union

def get_values(obj, only_add: str, prev_key: str = '') -> list:
    keys = []
    if type(obj) is dict:
        for key, item in obj.items():
            if key == only_add:
                keys.append(f"{prev_key}/{item}")
                prev_key = f"{prev_key}/{item}"
                
            elif isinstance(item, (list, dict)):
                keys.extend(get_values(item, only_add, prev_key))
    
    elif type(obj) is list:
        for item in obj:
            keys.extend(get_values(item, only_add, prev_key))
    return keys

Output of the function on your data

get_values(data, only_add="name")
>>> ['/default',
 '/name1',
 '/name1/subname1',
 '/name1/subname1/sub-subname1',
 '/name1/subname1/sub-subname2']

edited Sep 15, 2022 at 17:24

answered Sep 15, 2022 at 15:25

Lucas M. Uriarte

3,17611 silver badges25 bronze badges

6 Comments

GVX Over a year ago

Not quite, i just need the "name" keys' values :-)

Fedeco Over a year ago

Have you read the output requested ? @Bass asked for >>> ["/default", "/name1/subname1/sub-subname1", '/name1/subname1/sub-subname2", ] not >>> ['/data/name --> default', '/data/name --> name1', '/data/subobj/name --> subname1', '/data/subobj/subobj/name --> sub-subname1', '/data/subobj/subobj/name --> sub-subname2'] '/data/subobj/subobj/name --> sub-subname2']

tobias_k Over a year ago

This combines all the direct parent keys, but OP wants to combine all the name values in the parent dicts.

tobias_k Over a year ago

Also, did not check in detail, but why the instanceof check after the type checks? You already have cases for all types on the top level, so can't you just call the function again for all children?

Lucas M. Uriarte Over a year ago

@tobias_k, thank for your comments. I really misunderstood the question. I have finally corrected my answer. Thanks again

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