使用Python从此JSON对象中提取嵌套列表

Question

I'm using this python script ( in an attempt ) to extract a nested list from a JSON object.

import json
from collections import defaultdict
from pprint import pprint

with open('data-science.txt') as data_file:
    data = json.load(data_file)

locations = defaultdict(int)

for item in data['included']:
    location = item['attributes']
    print(location)

I get the following output:

{'name': 'Victoria', 'coord': [51.503378, -0.139134]}
{'name': 'United Kingdom', 'coord': None}
{'name': 'data science'}
{'CEO': None, 'abbreviation': None, 'logoUrl': None, 'title': 'Make IT London'}
{'name': 'Victoria', 'coord': [51.503378, -0.139134]}
{'name': 'United Kingdom', 'coord': None}
{'name': 'data science'}
{'CEO': None, 'abbreviation': None, 'logoUrl': None, 'title': 'Make IT London'}
{'name': 'Victoria', 'coord': [51.503378, -0.139134]}
{'name': 'United Kingdom', 'coord': None}
{'name': 'data science'}
{'CEO': None, 'abbreviation': None, 'logoUrl': None, 'title': 'Make IT London'}
{'name': 'Victoria', 'coord': [51.503378, -0.139134]}
{'name': 'United Kingdom', 'coord': None}
{'name': 'data science'}
{'CEO': None, 'abbreviation': None, 'logoUrl': None, 'title': 'Make IT London'}
{'name': 'Victoria', 'coord': [51.503378, -0.139134]}
{'name': 'United Kingdom', 'coord': None}
{'name': 'data mining'}
{'name': 'data analysis'}

But really what I want is the 'coord' list associated with an "id" .

A single record looks like this:

    {
        "id": 3,
        "type": "location",
        "attributes": {
            "name": "Victoria",
            "coord": [
                51.503378,
                -0.139134
            ]
        }
    },

How can I extract the only the "id": 3 and "coord": [ 51.503378, -0.139134 ] ?

Answer 1

This is a little bare-bones but may help. Baseline - you might want to use the get function in python. (See this: https://docs.python.org/2/library/stdtypes.html#dict.get )

I won't expand too much on the below code - it is fairly simple - but you can add some logic around it to check if id is None or if coord is None and do additional processing for your own purposes.

for record in data['included']:
    id = record.get('id', None)
    coord = record.get('attributes', {}).get('coord', None)

Answer 2

You have to access the sub-structure with its key:

coords = {}
for item in data['included']:
    coords[item['id']] = item['attributes']['coords']

Answer 3

>>> data
{'id': 3, 'attributes': {'coord': [51.503378, -0.139134], 'name': 'Victoria'}, 'type': 'location'}
>>> from operator import itemgetter
>>> my_id = itemgetter('id')
>>> attributes = itemgetter('attributes')
>>> coord = itemgetter('coord')
>>> 
>>> my_id(data), coord(attributes(data))
(3, [51.503378, -0.139134])
>>> {my_id(data) : coord(attributes(data))}
{3: [51.503378, -0.139134]}
>>> d = {}
>>> d[my_id(data)] = coord(attributes(data))
>>> d
{3: [51.503378, -0.139134]}
>>> 

Answer 4

I am assuming, the id and type are always provided through JSON response, and if type is location then coord will be given too:

location_map = {}

for item in data.get('included', [])
    if item['type'] == 'location':
        location_map[item['id']] = item['attributes']['coord']

print location_map

OR in more pythonic way:

location_map = {
    item['id']: item['attributes']['coord']
    for item in data.get('included', []) if item['type'] == 'location'
}
print location_map

For sample input:

[
  {
    "id": 3,
    "type": "location",
    "attributes": {
        "name": "Victoria",
        "coord": [
            51.503378,
            -0.139134
        ]
     }
  }
]

result would be:

{3: [51.503378, -0.139134]}

For reference see Dict Comprehensions: https://www.python.org/dev/peps/pep-0274/