Converting JSON to a CSV file with Python

In a previous post, I showed how to extract data from the Google Maps API, which leaves a series of JSON files, like this:

{"address_components":
[{"long_name":"576","short_name":"576","types":["street_number"]},
{"long_name":"Concord Road","short_name":"Concord Road","types":["route"]},{"long_name":"Glen Mills","short_name":"Glen Mills","types":["locality","political"]},{"long_name":"PA","short_name":"PA","types":...

Ideally we want selections from these as a CSV for manual review, and import into mapping software. First, we load a list of files:

import os
 
folder = 'G:\\maps\\churches\\db.tar\\db\\db'
 
files = []
for root, dirs, f in os.walk(folder):
    files = files + f

Then, we define a function which reads the contents of each file, and parses it as JSON, skipping non-JSON files:

import json
 
def js(fn):
  try:
    with open(fn, 'r') as f:
      contents = f.read()
      f.close()
      return json.loads(contents)
  except:
    return ''
 
text = [js(f) for f in files]

We can then easily retrieve rows as tuples – since JSON is typically a hierarchical format, you may need to manually filter these in some way.

csv_rows = \
  [(j['name'], \
   get(j, 'website'), \
   j['geometry']['location']['kb'], \
   j['geometry']['location']['jb'], \
   j['formatted_address']) for j in text]

Finally, we use a simple CSV API provided by Python to write the file. Typically values in CSV files are quoted where necessary and separated by commas, although this API lets you control that:

with open('maps.csv', 'wb') as csvfile:
 mapswriter = csv.writer(csvfile, delimiter=',',
                         quotechar='"', quoting=csv.QUOTE_MINIMAL)
  for r in csv_rows:
    mapswriter.writerow(r)

One of the great things about Python as a scripting language for data analysis is the host of APIs available to make this operation simple – as you can see this is quite easy, as it doesn’t require downloading any additional add-on libraries.

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2 comments ↓

#1 Eduardo on 08.03.13 at 1:48 pm

Hello,

I’m getting
“Traceback (most recent call last):
File “json2csv3.py”, line 30, in
mapswriter = csv.writer(csvfile, delimiter=’,’,
NameError: name ‘csv’ is not defined”

Do you know hot to fix it?

#2 Gary on 08.03.13 at 11:39 pm

Do
import csv

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