JSON confusion

[Terry Reedy]

On 8/17/2016 12:35 PM, Steve Simmons wrote:
> I'm trying to write a small utility to find the closest railway station
> to a given (UK) postcode but the result is in JSON and I'm not familiar
> with it. I've got as far as extracting the JSON object and I can print
> the first level elements ("success" and "result") but I've totally
> confused myself about how to delve into the rest of the data structure.
> Can anyone point me to a 'how-to' for tackling a fairly complex SJON
> object or give me some pointers. ... or maybe point out if I'm taking an
> unnecessarily complex approach. Initially, I'm Looking to extract
> 'stationname', 'distance' and one or two of the coordinate pairs. To be
> honest, I'd rather have some hints rather than the whole solution
> otherwise I'll not learn anything :-) SteveS def main():
>     import urllib
>     import urllib.request
>     import urllib.parse
>     import urllib.response
>     import json
add   import pprint


>     url
> ='https://data.gov.uk/data/api/service/transport/naptan_railway_stations/postcode?postcode=CT16+1ez&distance=2'
> req = urllib.request.urlopen(url)
>
>     req_json = req.read()
>     str_json = req_json.decode("utf-8")
>
>     p_json = json.loads(str_json)

This result is nexted dicts and lists

>     print(p_json)
>     print ('======================================')
>     print(repr(p_json))
>     print('SUCCESS: ',repr(p_json['success']))
>     print ('======================================')
>     print('RESULT : ',repr(p_json['result']))

Replace prints above with
pprint.pprint(p_json)
and you will see the better formatted

{'result': [{'atcocode': '9100DOVERP',
              'crscode': 'DVP',
              'distance': 881.148432224,
              'latlong': {'coordinates': [1.3052936134036113, 
51.12569875059288],
                          'crs': {'properties': {'name': 'EPSG4326'},
                                  'type': 'name'},
                          'type': 'Point'},
              'ospoint': {'coordinates': [631380.0, 141464.0],
                          'crs': {'properties': {'name': 'EPSG27700'},
                                  'type': 'name'},
                          'type': 'Point'},
              'stationname': 'Dover Priory Rail Station',
              'tiploccode': 'DOVERP'}],
  'success': True}

Use this in combination with Jon Ribbens' answer.


-- 
Terry Jan Reedy