store-dicts.md

Storing dictionaries for later use: JSON and Pickle

JSON

Saving:

import json
with open('data.json', 'w') as fp:
    json.dump(data, fp)

Supply extra arguments like sort_keys or indent to get a pretty result. The argument sort_keys will sort the keys alphabetically and indent will indent your data structure with indent=N spaces.

json.dump(data, fp, sort_keys=True, indent=4)

Loading:

with open('data.json', 'r') as fp:
    data = json.load(fp)

json.dump() vs json.dumps(), json.load() vs json.loads()

If you want to dump the JSON into a file/socket or whatever, then you should go for dump(). If you only need it as a string (for printing, parsing or whatever) then use dumps() (dump string). The functions with an s take string parameters. The others take file streams.

---

Pickle

Saving:

import cPickle as pickle
with open('data.p', 'wb') as fp:
    pickle.dump(data, fp)

Loading:

with open('data.p', 'rb') as fp:
    data = pickle.load(fp)