python json

Introduction
JSON (JavaScript Object Notation) is frequently used between a server and a web application. An example of JSON data:

{
    "persons": [
        {
            "city": "Seattle", 
            "name": "Brian"
        }, 
        {
            "city": "Amsterdam", 
            "name": "David"
        }
    ]
}

The json module enables you to convert between JSON and Python Objects.

Related course:
Data Analysis with Python Pandas

JSON conversion examples

Convert JSON to Python Object (Dict)
To convert JSON to a Python dict use this:

import json

json_data = '{"name": "Brian", "city": "Seattle"}'
python_obj = json.loads(json_data)
print python_obj["name"]
print python_obj["city"]

Convert JSON to Python Object (List)
JSON data can be directly mapped to a Python list.

import json

array = '{"drinks": ["coffee", "tea", "water"]}'
data = json.loads(array)

for element in data['drinks']:
    print element

Convert JSON to Python Object (float)
Floating points can be mapped using the decimal library.

import json
from decimal import Decimal

jsondata = '{"number": 1.573937639}'

x = json.loads(jsondata, parse_float=Decimal)
print x['number']

Convert JSON to Python Object (Example)
JSON data often holds multiple objects, an example of how to use that below:

import json
 
json_input = '{"persons": [{"name": "Brian", "city": "Seattle"}, {"name": "David", "city": "Amsterdam"} ] }'

try:
    decoded = json.loads(json_input)
 
    # Access data
    for x in decoded['persons']:
        print x['name']
 
except (ValueError, KeyError, TypeError):
    print "JSON format error"

Convert Python Object (Dict) to JSON
If you want to convert a Python Object to JSON use the json.dumps() method.

import json
from decimal import Decimal

d = {}
d["Name"] = "Luke"
d["Country"] = "Canada"

print json.dumps(d, ensure_ascii=False)
# result {"Country": "Canada", "Name": "Luke"}

Converting JSON data to Python objects
JSON data can be converted (deserialized) to Pyhon objects using the json.loads() function. A table of the mapping:

JSON	Python
object	dict
array	list
string	str
number (int)	int
number (real)	float
true	True
false	False
null	None

Pretty printing

If you want to display JSON data you can use the json.dumps() function.

import json

json_data = '{"name": "Brian", "city": "Seattle"}'
python_obj = json.loads(json_data)
print json.dumps(python_obj, sort_keys=True, indent=4)

More
Google Charts with JSON data