Common use-cases for pickle in Python

Question

I've looked at the pickle documentation, but I don't understand where pickle is useful.

What are some common use-cases for pickle?

Answer 1

To add a real-world example: The Sphinx documentation tool for Python uses pickle to cache parsed documents and cross-references between documents, to speed up subsequent builds of the documentation.

Answer 2

For the beginner (as is the case with me) it's really hard to understand why use pickle in the first place when reading the official documentation. It's maybe because the docs imply that you already know the whole purpose of serialization. Only after reading the general description of serialization have I understood the reason for this module and its common use cases. Also broad explanations of serialization disregarding a particular programming language may help: https://stackoverflow.com/a/14482962/4383472, What is serialization?, https://stackoverflow.com/a/3984483/4383472

Answer 3

I use pickling during web scrapping one of website at that time I want to store more than 8000k urls and want to process them as fast as possible so I use pickling because its output quality is very high.

you can easily reach to url and where you stop even job directory key word also fetch url details very fast for resuming the process.

Answer 4

Pickle is like "Save As.." and "Open.." for your data structures and classes. Let's say I want to save my data structures so that it is persistent between program runs.

Saving:

with open("save.p", "wb") as f:    
    pickle.dump(myStuff, f)        

Loading:

try:
    with open("save.p", "rb") as f:
        myStuff = pickle.load(f)
except:
    myStuff = defaultdict(dict)

Now I don't have to build myStuff from scratch all over again, and I can just pick(le) up from where I left off.

Answer 5

Minimal roundtrip example..

>>> import pickle
>>> a = Anon()
>>> a.foo = 'bar'
>>> pickled = pickle.dumps(a)
>>> unpickled = pickle.loads(pickled)
>>> unpickled.foo
'bar'

Edit: but as for the question of real-world examples of pickling, perhaps the most advanced use of pickling (you'd have to dig quite deep into the source) is ZODB: http://svn.zope.org/

Otherwise, PyPI mentions several: http://pypi.python.org/pypi?:action=search&term=pickle&submit=search

I have personally seen several examples of pickled objects being sent over the network as an easy to use network transfer protocol.

Answer 6

I can tell you the uses I use it for and have seen it used for:

• Game profile saves
• Game data saves like lives and health
• Previous records of say numbers inputed to a program

Those are the ones I use it for at least