json - How to export DataFrame to_json in append mode - Python Pandas? -


i have existing json file in format of list of dicts.

$cat output.json [{'a':1, 'b':2}, {'a':2, 'b':3}]

and have dataframe

df = pd.dataframe({'a':pd.series([1,2], index=list('cd')), \               "b":pd.series([3,4], index=list('cd')})

i want save "df" to_json append file output.json:

df.to_json('output.json', orient='records')  #  mode='a' not available to_json

* there append mode='a' to_csv, not to_json really.

the expected generated output.json file be:

    [{'a':1, 'b':2}, {'a':2, 'b':3}, {'a':1, 'b':3}, {'a':2, 'b':4}]

the existing file output.json can huge (say tetabytes), possible append new dataframe result without loading file?

no, can't append json file without re-writing whole file using pandas or json module. might able modify file "manually" opening file in a mode , seeking correct position , inserting data. wouldn't recommend though. better use file format other json if file going larger ram.

this answer might help. doesn't create valid json files (instead each line json string), goal similar yours.


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