Python JSON input order

Question

I am attempting to read a JSON file containing data which I want to keep in order as it is a mathematical equation which can't change. I have tried using OrderedDict() however this doesn't work (or I can't get it to work).

Here is the code I am using:

import json
from collections import OrderedDict

json_data = open('example3.json')
data = OrderedDict(json.load(json_data))

print (json.dumps(data))

Could anyone shine some light as to why this is not working?

Kind regards Craig

Just note that the json spec explicitely mentions that json objects (which translate to `dict`s in Python) are "an _unordered_ collection of key:value pairs" - IOW, you should __not__ rely on keys order in json. — bruno desthuilliers, Jan 06 '15 at 11:45

score 3 · Accepted Answer · answered Jan 06 '15 at 11:07

json.load will load the json data into a dictionary. You then convert this dictionary to an OrderedDict. Unfortunately, because it was a dictionary first the order could have already changed before it is "set" in the OrderedDict.

To load the json directly into an OrderedDict you can use the keyword argument object_pairs_hook with OrderedDict. See the documentation for more details.

import json
from collections import OrderedDict

json_data = open('example3.json')
data = json.load(json_data, object_pairs_hook=OrderedDict)

Python JSON input order

1 Answers1