Python basic syntax-JSON & Pickle

Scene

Example 1dic=Str ({' Age':' -'})f= Open ('text','W') F.write (DIC) F.close () Example 2f= Open ('text','R') Data=F.read ()Print(Eval (Data) [' Age'])

When we store the memory data object in a file, it is impossible to store the Dictionary object directly, it must be converted to the string format str (), when we read the dictionary format object stored in the file through the F.read () method, the reading is also a string that must be converted with the Eval () method, which is very Lou.

Two modules for serialization

• JSON, used to convert between string and Python data types
• Pickle for conversion between Python-specific types and Python data types

The JSON module provides four functions: dumps, dump, loads, load

The Pickle module provides four functions: dumps, dump, loads, load

JSON module

In the above scenario, the better approach is through the JSON module, because JSON represents a string that can be read by all languages, easily stored to disk, or transmitted over a network. JSON is not only a standard format, but also faster than XML, and can be read directly in the Web page, very convenient.

ImportJsondic= {' Age':' -'}#Write Filedata =Json.dumps (DIC) F= Open ('text','W') f.write (data) f.close ()#Read Filef = open ('text','R') Data=f.read () content=json.loads (data)Print(content[' Age'])

• JSON cannot convert functions and classes

Pickle Module

The problem with Pickle is the same as for all other programming language-specific serialization problems, that is, it can only be used in Python, and may be incompatible with each other in Python, so it's okay to save only those unimportant data with pickle and not successfully deserialize it.

ImportPickledeffoo ():Print('OK')#Write Filedata =pickle.dumps (foo) F= Open ('text','WB') f.write (data) f.close ()#Read Filef = open ('text','RB') Data=f.read () content=pickle.loads (data) content ()#Can ' t get attribute ' foo ' on <module ' __main__ ' from ' C:/users/lg/pycharmprojects/mystuff/march/day23/json_ module.py ' >

• Note: The write mode must be WB, RB
• Reading a file is an error because the function memory address cannot be found, so if you want to read it, the function must be in memory address.

Dump & Load Method

1. Dump

Import= {'age':'+ ' = open ('  text','w') json.dump (dic,f) f.close ()

• The process by which dump will be converted and written

2. Load

Import= open ('text','r'=  Json.load (f)print(data['age') f.close ()

• The process by which load will be converted and read

Python basic syntax-JSON & Pickle