Example of Python pickle module usage

The pickle module of python implements basic data sequencing and deserialization. Through the serialization operation of pickle module, we can save the object information running in the program to a file for permanent storage. Through the deserialization operation of the pickle module, we were able to create objects from the file that the program saved once before.

Basic interface:

　　pickle.dump(obj, file, [,protocol])

Note: save the object obj to the file file.

protocol is the version of the protocol used for serialization, 0: ASCII protocol. The serialized objects are represented by the printable ASCII code. 1: old-fashioned base 2 protocol; Version 2:2.3 introduces a new base 2 protocol that is more efficient than the previous one. Among them, protocol 0 and 1 are compatible with the old version of python. protocol defaults to 0.

file: class file object to which the object is saved. file must have an write() interface, and file can be either a file opened in 'w' or an StringIO object or any other object that implements the write() interface. If protocol > =1, the file object needs to be opened in base 2 mode.

pickle.load(file)
Comment: read a string from file and refactor it to the original python object.
file: class file object with read() and readline() interfaces.

A Simple Code

# use pickle The module saves the data object to a file   import pickle
data1 = {'a': [1, 2.0, 3, 4+6j], 'b': ('string', u'Unicode string'), 'c': None}
selfref_list = [1, 2, 3]

selfref_list.append(selfref_list)
output = open('data.pkl', 'wb') # Pickle dictionary using protocol 0. pickle.dump(data1, output) # Pickle the list using the highest protocol available. pickle.dump(selfref_list, output, -1)
output.close()

 

# use pickle The module is refactored from the file python object   import pprint, pickle
pkl_file = open('data.pkl', 'rb')
data1 = pickle.load(pkl_file)

pprint.pprint(data1)
data2 = pickle.load(pkl_file)

pprint.pprint(data2)
pkl_file.close()