CSV file to JSON file in Python

Question

I have read quite a lot of posts here and elsewhere, but I can't seem to find the solution. And I do not want to convert it online.

I would like to convert a CSV file to a JSON file (no nesting, even though I might need it in the future) with this code I found here:

import csv
import json

f = open( 'sample.csv', 'r' )
reader = csv.DictReader( f, fieldnames = ( "id","name","lat","lng" ) )
out = json.dumps( [ row for row in reader ] )
print out

Awesome, simple, and it works. But I do not get a .csv file, but a text output that if I copy and paste, is one long line.

I would need a .json that is readable and ideally saved to a .json file. Is this possible?

cloudfeet · Accepted Answer · 2012-10-18 09:38:49Z

3

To get more readable JSON, try the indent argument in dumps():

print json.dumps(..., indent=4)

However - to look more like the original CSV file, what you probably want is to encode each line separately, and then join them all up using the JSON array syntax:

out = "[\n\t" + ",\n\t".join([json.dumps(row) for row in reader]) + "\n]"

That should give you something like:

[
    {"id": 1, "name": "foo", ...},
    {"id": 2, "name": "bar", ...},
    ...
]

If you need help writing the result to a file, try this tutorial.

edited Oct 18, 2012 at 9:38

answered Oct 18, 2012 at 9:32

cloudfeet

13.1k2 gold badges61 silver badges62 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

digit Over a year ago

Thanks that worked, now I need to find out how to strucre the data in csv to get a nested json out of it. Thanks again

Peter Mortensen · Accepted Answer · 2016-11-06 21:25:37Z

1

If you want a more readable format of the JSON file, use it like this:

json.dump(output_value, open('filename','w'), indent=4, sort_keys=False)

edited Nov 6, 2016 at 21:25

Peter Mortensen

31.4k22 gold badges110 silver badges134 bronze badges

answered May 9, 2013 at 13:50

Mohan

97 bronze badges

Comments

Peter Mortensen · Accepted Answer · 2016-11-06 21:27:22Z

Here's a full script. This script uses the comma-separated values of the first line as the keys for the JSON output. The output JSON file will be automatically created or overwritten using the same file name as the input CSV file name just with the .csv file extension replaced with .json.

Example CSV file:

id,longitude,latitude
1,32.774,-124.401
2,32.748,-124.424
4,32.800,-124.427
5,32.771,-124.433

Python script:

csvfile = open('sample.csv', 'r')
jsonfile = open('sample.csv'.replace('.csv', '.json'), 'w')

jsonfile.write('{"' + 'sample.csv'.replace('.csv', '') + '": [\n') # Write JSON parent of data list
fieldnames = csvfile.readline().replace('\n','').split(',')        # Get fieldnames from first line of csv
num_lines = sum(1 for line in open('sample.csv')) - 1              # Count total lines in csv minus header row

reader = csv.DictReader(csvfile, fieldnames)
i = 0
for row in reader:
  i += 1
  json.dump(row, jsonfile)
  if i < num_lines:
    jsonfile.write(',')
  jsonfile.write('\n')
jsonfile.write(']}')

Collectives™ on Stack Overflow

CSV file to JSON file in Python

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related