递归访问嵌套字典的路径和值

Question

In Python 2.7, how does one dynamically access and print out the keys and values of a nested dictionary? Here's a nonsensical example: https://jsoneditoronline.org/?id=da7a486dc2e24bf8b94add9f04c71b4d

Normally, I would do something like:

import json

json_sample = 'sample_dict.json'
json_file = open(json_sample, 'r')
json_data = json.load(json_file)

items = json_data['sample_dict']

for item in items:
    dict_id = item['dict_id']
    person = item['person']['person_id']
    family = item['family']['members']

    print dict_id
    print person
    print family

I can hard code it like this and it'll give me desirable results, but how would I access each of the keys and values dynamically so that:

• The first row just prints the keys ( dict_id , person['person_id'] , person['name'] , family['members']['father'] )
• The second row prints the values respectively (5, 15, "Martin", "Jose")

The end result should be in a CSV file.

Answer 1

You can use a recursive visitor/generator which returns all the path/value pairs of the leaves:

def visit_dict(d, path=[]):
    for k, v in d.items():
        if not isinstance(v, dict):
            yield path + [k], v
        else:
            yield from visit_dict(v, path + [k])

(replace the yield from ... with the appropriate equivalent if using Python < 3.4)

Getting the keys:

>>> ','.join('/'.join(k) for k, v in visit_dict(json_data['sample_dict'][0]))
'dict_id,person/person_id,person/name,person/age,family/person_id,family/members/father,family/members/mother,family/members/son,family/family_id,items_id,furniture/type,furniture/color,furniture/size,furniture/purchases'

and the values:

>>> ','.join(str(v) for k, v in visit_dict(json_data['sample_dict'][0]))
'5,15,Martin,18,20,Jose,Maddie,Jerry,2,None,Chair,Brown,Large,[]'