Unintentional random order in a list

Question

I am trying to build a list with data of a JSON object. However the order of the list does not match the oder of the JSON object and changes nearly everytime I run the code.

{
    "project":{
        "Projektnamen":{
            "Server":{
                "Server1":{
                    ...
                },
                "Server2":{
                    ...
                },
                "Server3":{
                    ...
                }
            }
        }
    }
}

with open('json_data.json') as json_file:
    # json CONFIG_JSON Konfigurationsdatei
    CONFIG_JSON = json.load(json_file)

for key in CONFIG_JSON["project"]["Projektnamen"]["Server"]:
    servernamen.append(key)

Expected result: servernamen = [Server1, Server2, Server3]

However the order always changes. Last result: servernamen = [Server3, Server1, Server2]

probably before Python 3.6 array (or rather dictionary) doesn't have to keep order. If you need order then better keep it as list. — furas, Jun 27 '19 at 06:37
@TheScientificMethod That information is out of date. Please see https://stackoverflow.com/a/47881325/4014959 OTOH, the JSON specification doesn't require `{}` objects to retain order, so it's generally *not* wise to have a data flow that expects them to retain order. — PM 2Ring, Jun 27 '19 at 08:07

score 1 · Accepted Answer · answered Jun 27 '19 at 06:53

1

You can import your JSON data already sorted by using collections.OrderedDict and the arguments of json.load:

from collections import OrderedDict
import json


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

answered Jun 27 '19 at 06:53

wencakisa

5,850
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schmutov · Answer 2 · 2019-06-27T06:51:20.897

0

json.loads deserializes JSON into a dictionary object, which is a hash table that is not ordered.

You can use OrderedDict from collections to sort keys. Example

from collections import OrderedDict

d = {'banana': 3, 'apple':4, 'pear': 1, 'orange': 2}
new_d = OrderedDict(sorted(d.items()))

print(new_d)
# OrderedDict([('apple', 4), ('banana', 3), ('orange', 2), ('pear', 1)])

edited Jun 27 '19 at 06:51

answered Jun 27 '19 at 06:44

schmutov

207
1
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Is there a way to load the JSON in order? – SethFrkinRollins Jun 27 '19 at 06:49
Solution added in response – schmutov Jun 27 '19 at 06:52

Unintentional random order in a list

2 Answers2