Save a dictionary to a file (alternative to pickle) in Python?

Question

Answered I ended up going with pickle at the end anyway

Ok so with some advice on another question I asked I was told to use pickle to save a dictio

Answer 1

The YAML format (via pyyaml) might be a good option for you:

http://en.wikipedia.org/wiki/Yaml

http://pypi.python.org/pypi/PyYAML

Answer 2

While I'd suggest pickle, if you want an alternative, you can use klepto.

>>> init = {'y': 2, 'x': 1, 'z': 3}
>>> import klepto
>>> cache = klepto.archives.file_archive('memo', init, serialized=False)
>>> cache        
{'y': 2, 'x': 1, 'z': 3}
>>>
>>> # dump dictionary to the file 'memo.py'
>>> cache.dump() 
>>> 
>>> # import from 'memo.py'
>>> from memo import memo
>>> print memo
{'y': 2, 'x': 1, 'z': 3}

With klepto, if you had used serialized=True, the dictionary would have been written to memo.pkl as a pickled dictionary instead of with clear text.

You can get klepto here: https://github.com/uqfoundation/klepto

dill is probably a better choice for pickling then pickle itself, as dill can serialize almost anything in python. klepto also can use dill.

You can get dill here: https://github.com/uqfoundation/dill

Answer 3

Sure, save it as CSV:

import csv
w = csv.writer(open("output.csv", "w"))
for key, val in dict.items():
    w.writerow([key, val])

Then reading it would be:

import csv
dict = {}
for key, val in csv.reader(open("input.csv")):
    dict[key] = val

Another alternative would be json (json for version 2.6+, or install simplejson for 2.5 and below):

>>> import json
>>> dict = {"hello": "world"}
>>> json.dumps(dict)
'{"hello": "world"}'

Answer 4

Although, unlike pp.pprint(the_dict), this won't be as pretty, will be run together, str() at least makes a dictionary savable in a simple way for quick tasks:

f.write( str( the_dict ) )

Answer 5

You asked

Ill give it a shot. How do I specify what file to dump it to/load it from?

Apart from writing to a string, the json module provides a dump()-method, which writes to a file:

>>> a = {'hello': 'world'}
>>> import json
>>> json.dump(a, file('filename.txt', 'w'))
>>> b = json.load(file('filename.txt'))
>>> b
{u'hello': u'world'}

There is a load() method for reading, too.

Answer 6

The most common serialization format for this nowadays is JSON, which is universally supported and represents simple data structures like dictionaries very clearly.

>>> members = {'Starspy' : 'SHSN4N', 'Test' : 'Test1'}
>>> json.dumps(members)
'{"Test": "Test1", "Starspy": "SHSN4N"}'
>>> json.loads(json.dumps(members))
{u'Test': u'Test1', u'Starspy': u'SHSN4N'}