Loading and parsing a JSON file with multiple JSON objects

Question

I am trying to load and parse a JSON file in Python. But I’m stuck trying to load the file:

import json
json_data = open('file')
data = json.load(json_data)

Yields:

ValueError: Extra data: line 2 column 1 - line 225116 column 1 (char 232 - 160128774)

I looked at 18.2. json — JSON encoder and decoder in the Python documentation, but it’s pretty discouraging to read through this horrible-looking documentation.

First few lines (anonymized with randomized entries):

{"votes": {"funny": 2, "useful": 5, "cool": 1}, "user_id": "harveydennis", "name": "Jasmine Graham", "url": "http://example.org/user_details?userid=harveydennis", "average_stars": 3.5, "review_count": 12, "type": "user"}
{"votes": {"funny": 1, "useful": 2, "cool": 4}, "user_id": "njohnson", "name": "Zachary Ballard", "url": "https://www.example.com/user_details?userid=njohnson", "average_stars": 3.5, "review_count": 12, "type": "user"}
{"votes": {"funny": 1, "useful": 0, "cool": 4}, "user_id": "david06", "name": "Jonathan George", "url": "https://example.com/user_details?userid=david06", "average_stars": 3.5, "review_count": 12, "type": "user"}
{"votes": {"funny": 6, "useful": 5, "cool": 0}, "user_id": "santiagoerika", "name": "Amanda Taylor", "url": "https://www.example.com/user_details?userid=santiagoerika", "average_stars": 3.5, "review_count": 12, "type": "user"}
{"votes": {"funny": 1, "useful": 8, "cool": 2}, "user_id": "rodriguezdennis", "name": "Jennifer Roach", "url": "http://www.example.com/user_details?userid=rodriguezdennis", "average_stars": 3.5, "review_count": 12, "type": "user"}

Asked By: Pi_

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Source

Answer 1

You have a JSON Lines format text file. You need to parse your file line by line:

import json

data = []
with open('file') as f:
    for line in f:
        data.append(json.loads(line))

Each line contains valid JSON, but as a whole, it is not a valid JSON value as there is no top-level list or object definition.

Note that because the file contains JSON per line, you are saved the headaches of trying to parse it all in one go or to figure out a streaming JSON parser. You can now opt to process each line separately before moving on to the next, saving memory in the process. You probably don’t want to append each result to one list and then process everything if your file is really big.

If you have a file containing individual JSON objects with delimiters in-between, use How do I use the 'json' module to read in one JSON object at a time? to parse out individual objects using a buffered method.

Answered By: Martijn Pieters

Answer 2

That is ill-formatted. You have one JSON object per line, but they are not contained in a larger data structure (ie an array). You’ll either need to reformat it so that it begins with [ and ends with ] with a comma at the end of each line, or parse it line by line as separate dictionaries.

Answered By: Daniel Roseman

Answer 3

for those stumbling upon this question: the python jsonlines library (much younger than this question) elegantly handles files with one json document per line. see https://jsonlines.readthedocs.io/

Answered By: wouter bolsterlee

Answer 4

In case you are using pandas and you will be interested in loading the json file as a dataframe, you can use:

import pandas as pd
df = pd.read_json('file.json', lines=True)

And to convert it into a json array, you can use:

df.to_json('new_file.json')

Answered By: arunppsg

Loading and parsing a JSON file with multiple JSON objects

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