The pickle module
This module is used to serialize data; that is, convert data to and from character strings, so that they can be stored on file or sent over a network. It’s a quite a bit slower than marshal, but it can handle class instances, shared elements, and recursive data structures, among other things.
There’s also a faster C implementatation available, cPickle, which can usually be used as a drop-in replacement.
Example: Using the pickle module
# File: pickle-example-1.py import pickle value = ( "this is a string", [1, 2, 3, 4], ("more tuples", 1.0, 2.3, 4.5), "this is yet another string" ) data = pickle.dumps(value) # intermediate format print type(data), len(data) print "-"*50 print data print "-"*50 print pickle.loads(data)
<type 'string'> 121
--------------------------------------------------
(S'this is a string'
p0
(lp1
I1
aI2
aI3
aI4
a(S'more tuples'
p2
F1.0
F2.3
F4.5
tp3
S'this is yet another string'
p4
tp5
.
--------------------------------------------------
('this is a string', [1, 2, 3, 4], ('more tuples',
1.0, 2.3, 4.5), 'this is yet another string')
On the other hand, pickle cannot handle code objects (but see the copy_reg module for a way to fix this).
By default, pickle uses a text-based format. You can also use a binary format, in which numbers and binary strings are stored in a compact binary format. The binary format usually results in smaller files.
Example: Using the pickle module in binary mode
# File: pickle-example-2.py import pickle import math value = ( "this is a long string" * 100, [1.2345678, 2.3456789, 3.4567890] * 100 ) # text mode data = pickle.dumps(value) print type(data), len(data), pickle.loads(data) == value # binary mode data = pickle.dumps(value, 1) print type(data), len(data), pickle.loads(data) == value
rendered by a django application. hosted by webfaction.