Sorting JSON data by keys value

Question

I am currently getting JSON data from the discogs API (mp3 tag data) and wish to sort the results by the key's value. In this case I am trying to get data for a Guns n Roses song and the output has 1988 as the first one while the data actually has a record from 1987. How can I sort this data so that I can get to the sorted data by year (olderst to newest). The code below sorts by either key or value but thats not what I intended to get. Please help.

import json
import urllib2
request = urllib2.Request('http://api.discogs.com/database/search?sort=year&sort_order=asc&artist=%22Guns+N%27+Roses%22&track=%22Sweet+Child+O%27+Mine%22&format_exact=Album&type=master')
request.add_header('User-Agent','Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)')
request.add_header('Content-Type','application/json')
response = urllib2.urlopen(request)
json_raw= response.readlines()
json_object = json.loads(json_raw[0])



for row in json_object['results']:
    try:
        from operator import itemgetter
        for k, v in sorted(row.items(), key=itemgetter(0)):
            print k, v
    except KeyError: 
        pass

I'd help if you included a sample of the JSON data..

Martijn Pieters
– Martijn Pieters

2012-11-18 08:25:23 +00:00
Commented Nov 18, 2012 at 8:25 — Martijn Pieters
– Martijn Pieters, Commented Nov 18, 2012 at 8:25
By the looks of it, you are using this API.

Martijn Pieters
– Martijn Pieters

2012-11-18 08:33:03 +00:00
Commented Nov 18, 2012 at 8:33 — Martijn Pieters
– Martijn Pieters, Commented Nov 18, 2012 at 8:33

Ashwini Chaudhary · Accepted Answer · 2017-03-29 09:48:28Z

13

You could use list-comprehension and sorted() function for this:

# filter  json_object['results']  first, as some of the items are missing the key 'year'

In [33]: results = [x for x in json_object['results'] if 'year' in x]

In [34]: sorted(results, key=lambda x: x['year'])

or :

In [79]: from operator import itemgetter

In [80]: sorted(results, key=itemgetter('year'))

edited Mar 29, 2017 at 9:48

answered Nov 18, 2012 at 8:39

Ashwini Chaudhary

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1 Comment

Prem Minister Over a year ago

Than you, this works like a charm, as you can tell, I am a newbie and have a long way to go..

Martijn Pieters · Accepted Answer · 2013-01-14 22:10:26Z

1

To sort a list of dictionaries, use a methodcaller with the key on which to sort; you want to sort the results list, not the contained dictionaries. Moreover, some of the entries do not have a year, and that could lead to errors:

from operator import methodcaller

for row in sorted(json_object['results'], key=methodcaller('get', 'year', None)):
    # process the row dictionary

The methodcaller definition will basically do a entry.get('year', None) for each entry in json_object['results'], giving the sorted method the value to sort on.

You should not use readlines() to read your JSON response, it'll mis-interpret newlines. Let the json library do the reading instead (note the .load(), no s at the end):

response = urllib2.urlopen(request)
json_object = json.load(response)

edited Jan 14, 2013 at 22:10

answered Nov 18, 2012 at 8:29

Martijn Pieters

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5 Comments

Prem Minister Over a year ago

I am new to this forum and I am unable to post the JSON as it says I have few characters left to post...

Martijn Pieters Over a year ago

Take a look at How do I format my code blocks? for more help.

Prem Minister Over a year ago

I am not sure what I am doing wrong, but when I run this now, I get an error:

Prem Minister Over a year ago

C:\Python27>python test2.py Traceback (most recent call last): File "test2.py", line 11, in <module> for row in sorted(json_object['results'], key=itemgetter('year')): KeyError: 'year'

Martijn Pieters Over a year ago

@PremMinister: I tested the code some more, and made an update. I switched techniques a little, actually.

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