json - How to convert a list of numbers to jsonarray in Python

Question

I have a row in following format:

row = [1L,[0.1,0.2],[[1234L,1],[134L,2]]]

Now, what I want is to write the following in the file:

[1,[0.1,0.2],[[1234,1],[134,2]]]

Basically converting above into a jsonarray?

Is there an built-in method, library, or function in Python to "dump" array into json array?

Also note that I don't want "L" to be serialized in my file.

Answer 1

Use the json module to produce JSON output:

import json

with open(outputfilename, 'wb') as outfile:
    json.dump(row, outfile)

This writes the JSON result directly to the file (replacing any previous content if the file already existed).

If you need the JSON result string in Python itself, use json.dumps() (added s, for 'string'):

json_string = json.dumps(row)

The L is just Python syntax for a long integer value; the json library knows how to handle those values, no L will be written.

Demo string output:

>>> import json
>>> row = [1L,[0.1,0.2],[[1234L,1],[134L,2]]]
>>> json.dumps(row)
'[1, [0.1, 0.2], [[1234, 1], [134, 2]]]'