Create JSONL with Python

Question

I can't figure out how to create JSONL using Python3.

test = [{'a': 'b'}, {'a': 'b'}, {'a': 'b'}]

with open("data.json", 'w') as f:
    for item in test:
        json.dump(item, f)

with open("data.json") as f:
    for line in f:
        // only 1 line here! 
        print(line)

// prints
{"a": "b"}{"a": "b"}{"a": "b"}

I've tried using indent option to dump but it appears to make no different and the separators option don't seem to be a great usecase. Not sure what I'm missing here?

Do you want each item in test as a new line in the output file? — Rakesh
– Rakesh, Commented Jul 17, 2019 at 9:03

Rakesh · Accepted Answer · 2019-07-17 09:09:47Z

26

Use .write with newline \n

Ex:

import json
test = [{'a': 'b'}, {'a': 'b'}, {'a': 'b'}]

with open("data.json", 'w') as f:
    for item in test:
        f.write(json.dumps(item) + "\n")

with open("data.json") as f:
    for line in f:
        print(line)

answered Jul 17, 2019 at 9:09

Rakesh

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2 Comments

rix Over a year ago

You're right, was overthinking it - that does seem to be valid JSONL. Thanks

Ido Bleicher Over a year ago

You can also use jsonlines, or ndjson :)

David Beauchemin · Accepted Answer · 2024-08-02 23:00:42Z

1

You can also use Pandas to do it.

import pandas as pd

df_test = pd.DataFrame([{'a': 'b'}, {'a': 'b'}, {'a': 'b'}])

with open("data.jsonl", "w") as f:
    f.write(df_test.to_json(orient="records", lines=True, force_ascii=False))

answered Aug 2, 2024 at 23:00

David Beauchemin

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