Python Parse JSON array

Question

I’m trying to put together a small python script that can parse out array’s out of a large data set. I’m looking to pull a few key:values from each object so that I can play with them later on in the script. Here’s my code:

# Load up JSON Function
import json

# Open our JSON file and load it into python
input_file = open ('stores-small.json')
json_array = json.load(input_file)

# Create a variable that will take JSON and put it into a python dictionary
store_details = [
        ["name"],
        ["city"]
    ]

# Learn how to loop better =/
for stores in [item["store_details"] for item in json_array]

Here’s the sample JSON Data:

[
  {
    "id": 1000,
    "type": "BigBox",
    "name": "Mall of America",
    "address": "340 W Market",
    "address2": "",
    "city": "Bloomington",
    "state": "MN",
    "zip": "55425",
    "location": {
      "lat": 44.85466,
      "lon": -93.24565
    },
    "hours": "Mon: 10-9:30; Tue: 10-9:30; Wed: 10-9:30; Thurs: 10-9:30; Fri: 10-9:30; Sat: 10-9:30; Sun: 11-7",
    "services": [
      "Geek Squad Services",
      "Best Buy Mobile",
      "Best Buy For Business"
    ]
  },
  {
    "id": 1002,
    "type": "BigBox",
    "name": "Tempe Marketplace",
    "address": "1900 E Rio Salado Pkwy",
    "address2": "",
    "city": "Tempe",
    "state": "AZ",
    "zip": "85281",
    "location": {
      "lat": 33.430729,
      "lon": -111.89966
    },
    "hours": "Mon: 10-9; Tue: 10-9; Wed: 10-9; Thurs: 10-9; Fri: 10-10; Sat: 10-10; Sun: 10-8",
    "services": [
      "Windows Store",
      "Geek Squad Services",
      "Best Buy Mobile",
      "Best Buy For Business"
    ]}
  ]

Asked By: RomeNYRR

||

Source

Answer 1

In your for loop statement, Each item in json_array is a dictionary and the dictionary does not have a key store_details. So I modified the program a little bit

import json

input_file = open ('stores-small.json')
json_array = json.load(input_file)
store_list = []

for item in json_array:
    store_details = {"name":None, "city":None}
    store_details['name'] = item['name']
    store_details['city'] = item['city']
    store_list.append(store_details)

print(store_list)

Answered By: yash

Answer 2

If you arrived at this question simply looking for a way to read a json file into memory, then use the built-in json module.

with open(file_path, 'r') as f:
    data = json.load(f)

If you have a json string in memory that needs to be parsed, use json.loads() instead:

data = json.loads(my_json_string)

Either way, now data is converted into a Python data structure (list/dictionary) that may be (deeply) nested and you’ll need Python methods to manipulate it.

If you arrived here looking for ways to get values under several keys as in the OP, then the question is about looping over a Python data structure. For a not-so-deeply-nested data structure, the most readable (and possibly the fastest) way is a list / dict comprehension. For example, for the requirement in the OP, a list comprehension does the job.

store_list = [{'name': item['name'], 'city': item['city']} for item in json_array]
# [{'name': 'Mall of America', 'city': 'Bloomington'}, {'name': 'Tempe Marketplace', 'city': 'Tempe'}]

Other types of common data manipulation:

For a nested list where each sub-list is a list of items in the json_array.

store_list = [[item['name'], item['city']] for item in json_array]
# [['Mall of America', 'Bloomington'], ['Tempe Marketplace', 'Tempe']]

For a dictionary of lists where each key-value pair is a category-values in the json_array.

store_data = {'name': [], 'city': []}
for item in json_array:
    store_data['name'].append(item['name'])
    store_data['city'].append(item['city'])
# {'name': ['Mall of America', 'Tempe Marketplace'], 'city': ['Bloomington', 'Tempe']}

For a "transposed" nested list where each sub-list is a "category" in json_array.

store_list = list(store_data.values())
# [['Mall of America', 'Tempe Marketplace'], ['Bloomington', 'Tempe']]

Answered By: cottontail

Python Parse JSON array

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