Sorting a Json File by a Certain Key

There are several steps:

• Read the file using json.load()
• Sort the list of objects using list.sort()
• Use a key-function to specify the sort field.
• Use operator.itemgetter() to extract the field of interest
• Write the data with json.dump()

Here's some code to get you started:

import json, operator

s = '''\
[
  {"CarValue": "59", "ID": "100043"},
  {"CarValue": "59", "ID": "100013"}
]
'''

data = json.loads(s)
data.sort(key=operator.itemgetter('ID'))
print(json.dumps(data, indent=2))

This outputs:

[
  {
    "CarValue": "59",
    "ID": "100013"
  },
  {
    "CarValue": "59",
    "ID": "100043"
  }
]

For your application, open the input file and use json.load() instead of json.loads(). Likewise, open a output file and use json.dump() instead of json.dumps(). You can drop the indent parameter as well, that is just to make the output look nicely formatted.

simple and probably faster in case of large data - pandas.DataFrame.to_json

>>> import pandas as pd
>>> unsorted = pd.read_json("test.json")
>>> (unsorted.sort_values("ID")).to_json("sorted_test.json")
>>> sorted = unsorted.sort_values("ID")
>>> sorted
   CarValue      ID
1        59  100013
0        59  100043
>>> sorted.to_json("n.JSON")