An object serialization module for Python. Use this tag together with the Python tag for questions related to storing or loading objects with Pickle.
Pickle provides a powerful set of tools for serializing and de-serializing Python objects.
Questions tagged [pickle]
4130 questions
469
votes
10 answers
How can I use pickle to save a dict?
I have looked through the information that the Python docs give, but I'm still a little confused. Could somebody post sample code that would write a new file then use pickle to dump a dictionary into it?
Chachmu
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289
votes
8 answers
Python multiprocessing PicklingError: Can't pickle
I am sorry that I can't reproduce the error with a simpler example, and my code is too complicated to post. If I run the program in IPython shell instead of the regular Python, things work out well.
I looked up some previous notes on this problem.…
Vendetta
- 13,178
- 19
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- 111
289
votes
2 answers
Using pickle.dump - TypeError: must be str, not bytes
I'm using python3.3 and I'm having a cryptic error when trying to pickle a simple dictionary.
Here is the code:
import os
import pickle
from pickle import *
os.chdir('c:/Python26/progfiles/')
def storvars(vdict):
f =…
John Rowland
- 3,069
- 2
- 13
- 7
288
votes
5 answers
Saving an Object (Data persistence)
I've created an object like this:
company1.name = 'banana'
company1.value = 40
I would like to save this object. How can I do that?
Peterstone
- 5,777
- 13
- 37
- 48
246
votes
9 answers
Storing Python dictionaries
I'm used to bringing data in and out of Python using CSV files, but there are obvious challenges to this. Are there simple ways to store a dictionary (or sets of dictionaries) in a JSON or pickle file?
For example:
data = {}
data ['key1'] =…
mike
- 19,373
- 28
- 72
- 93
225
votes
12 answers
Can't pickle when using multiprocessing Pool.map()
I'm trying to use multiprocessing's Pool.map() function to divide out work simultaneously. When I use the following code, it works fine:
import multiprocessing
def f(x):
return x*x
def go():
pool = multiprocessing.Pool(processes=4) …
ventolin
- 2,843
- 3
- 16
- 24
215
votes
16 answers
Serializing class instance to JSON
I am trying to create a JSON string representation of a class instance and having difficulty. Let's say the class is built like this:
class testclass:
value1 = "a"
value2 = "b"
A call to the json.dumps is made like this:
t =…
ferhan
- 2,211
- 2
- 12
- 9
190
votes
18 answers
Multiprocessing: How to use Pool.map on a function defined in a class?
When I run something like:
from multiprocessing import Pool
p = Pool(5)
def f(x):
return x*x
p.map(f, [1,2,3])
it works fine. However, putting this as a function of a class:
class calculate(object):
def run(self):
def f(x):
…
Mermoz
- 12,738
- 16
- 53
- 81
169
votes
7 answers
Pickle incompatibility of numpy arrays between Python 2 and 3
I am trying to load the MNIST dataset linked here in Python 3.2 using this program:
import pickle
import gzip
import numpy
with gzip.open('mnist.pkl.gz', 'rb') as f:
l = list(pickle.load(f))
print(l)
Unfortunately, it gives me the…
Neil G
- 28,787
- 31
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- 234
146
votes
7 answers
Saving and loading objects and using pickle
I´m trying to save and load objects using pickle module.
First I declare my objects:
>>> class Fruits:pass
...
>>> banana = Fruits()
>>> banana.color = 'yellow'
>>> banana.value = 30
After that I open a file called 'Fruits.obj'(previously I…
Peterstone
- 5,777
- 13
- 37
- 48
144
votes
8 answers
Why do I get "Pickle - EOFError: Ran out of input" reading an empty file?
I am getting an interesting error while trying to use Unpickler.load(), here is the source code:
open(target, 'a').close()
scores = {};
with open(target, "rb") as file:
unpickler = pickle.Unpickler(file);
scores = unpickler.load();
if…
Magix
- 3,557
- 3
- 18
- 43
142
votes
2 answers
Unpickling a python 2 object with python 3
I'm wondering if there is a way to load an object that was pickled in Python 2.4, with Python 3.4.
I've been running 2to3 on a large amount of company legacy code to get it up to date.
Having done this, when running the file I get the following…
NDevox
- 3,751
- 4
- 18
- 32
141
votes
6 answers
best way to preserve numpy arrays on disk
I am looking for a fast way to preserve large numpy arrays. I want to save them to the disk in a binary format, then read them back into memory relatively fastly. cPickle is not fast enough, unfortunately.
I found numpy.savez and numpy.load. But…
Vendetta
- 13,178
- 19
- 71
- 111
137
votes
9 answers
Common use-cases for pickle in Python
I've looked at the pickle documentation, but I don't understand where pickle is useful.
What are some common use-cases for pickle?
satoru
- 27,201
- 27
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135
votes
7 answers
Pickle or json?
I need to save to disk a little dict object whose keys are of the type str and values are ints and then recover it. Something like this:
{'juanjo': 2, 'pedro':99, 'other': 333}
What is the best option and why? Serialize it with pickle or with…
Juanjo Conti
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