10 Python standard library concise tutorial Table of Contents
1. Operating System Interface
2. File wildcards
3. Command Line Parameters
4. Error output redirection and program termination
5 String Matching
6. Mathematics
7. Internet access
8. Date and Time
9. Data Compression
10 Performance Measurement
11 Quality Control
1. Operating System Interface
The Python built-in (built-in) function is created with the running of the python interpreter. In Python programs, you can call these functions at any time without defining them. The most common built-in functions are: The Python built-in (built-in) functions are created with the running of the
Detailed tutorial on regular expressions in Python, python Regular Expressions
1. Understand Regular Expressions
A regular expression is a logical formula for string operations. It uses predefined characters and combinations of these specific characters to form a "rule string ", this "rule string" is used to express a filtering logic for strings.
Regular Expressi
= User.objects.skip(10).limit(5)Aggregate operations
Engine provides aggregation operations for some databases.
You can use the count method of QuerySet or the Python method to calculate the number of statistical results:
num_users = len(User.objects)num_users = User.objects.count()
Other aggregate operations.Sum:
yearly_expense = Employee.objects.sum('salary')
Average:
mean_age = User.objects.average('age')Advanced Query
Sometimes multiple condition
scrolls down. The image disappears when the page scrolls over the location of the image. We can background-attachment prevent this scrolling by attributes. With this property, you can declare that the image is fixed in relation to the visible area (fixed) and therefore not affected by scrolling:Body { background-image: url ("Python.png"); background-repeat: no-repeat; background-attachment:fixed;}Prevent Background Map Scrolling I believe everyone is also often seen, especially some ann
Course Cataloguewhat 01.scrapy is. mp4python Combat-02. Initial use of Scrapy.mp4The basic use steps of Python combat -03.scrapy. mp4python Combat-04. Introduction to Basic Concepts 1-scrapy command-line tools. mp4python Combat-05. This concept introduces the important components of 2-scrapy. mp4python Combat-06. Basic concepts introduce the important objects in 3-scrapy. mp4python combat -07.scrapy built-i
Concise Python tutorial --- 15. More Python content
Special Method
Some methods have special meanings in the class, which has been mentioned earlier. For example, the _ init _ method and the _ del _ method.
These special methods are very useful. For example, you want your class objects to use indexes, such as OBJ [Key], you can implement the _ getitem _ method i
Python tutorial 11 -- Python decorator
A function is also an object, and a function object can be assigned to a variable. Therefore, a function can also be called through a variable.
The function object has a (Double underline + name + double underline) attribute. You can get the function name:
Now, let's assume that we want to enhance the functions of the now (
Basic tutorial for getting started with Python (learningPython) -- 4.2Python's count loop body for statement. Another type of loop body structure in Python is the counting loop body for. some statement blocks are executed for a certain number of times through the for loop. the syntax structure is as follows. Another type of loop body structure of
1, Liaoche's official websiteHttp://www.liaoxuefeng.com/wiki/001374738125095c955c1e6d8bb493182103fac9270762a000/ 001386818214042e9c46552422e42d8a00f019e088506ce0002, an Introduction to Interactive programming in PythonHttps://www.coursera.org/learn/interactive-python-13. Cocode Python Programming Forumhttp://cocode.cc/4. The Flask MegaHttps://blog.miguelgrinberg.
Sequence common operations of notes in the basic python tutorial, and python Sequence
Index
All the elements in the sequence are numbered-starting from 0. When a negative index is used, Python starts counting from the right, that is, from the last element. The position number of the last element is-1. in addition, a
After you configure environment variables, you can typically call Python directly from Python or by specifying a python version number.
The Python interpreter operates like a Unix shell: it interactively interprets and executes commands when using a terminal device (TTY) as a standard input call, reads the f
How many times have you been stuck in a situation where you have to change someone else's code? If you're part of a development team, you're more than you want to be in this situation. However, Python has a neat debugging feature (like most other languages), which is handy in this case. This is a quick tutorial and hopefully it will make your coding life easier.1. A messy procedure
For the purposes of this
Use the commands in the PDB module in Python to debug the Python code tutorial, pythonpdb
How many times have you had to change others' code? If you are a member of a development team, you may encounter more times than you want. However, Python has a neat debugging feature (like most other languages), which is very con
Tutorial on using Python scripts to operate tables under Gnumeric, gnumericpython
About Gnumeric
Gnumeric is a powerful and easy-to-use spreadsheet software on the linux platform. It is consistent with other commonly used spreadsheet software such as Excel in terms of style. Gnumeric's current stable version is 1.2.13, and its support for Chinese characters is quite mature. According to official information
configuration filetutorial/: The Python module for the project, which will refer to code from here tutorial/items.py: Project's Items file tutorial/pipelines.py: Pipelines file for the project tutorial/ settings.py: Project Settings file tutorial/spiders/: directory where r
Using 70 lines of Python code to implement a recursive descent parser tutorial, 70 lines of python
Step 1: Tagging
The first step in processing an expression is to convert it to a list containing independent symbols. This step is very simple and not the focus of this article, so I have omitted a lot here.First, I define some tags (numbers are not in this box, the
Project
tutorial/: The project's Python module, which will reference the code from here
tutorial/items.py: Project Items file
tutorial/pipelines.py: Project's Pipelines file
tutorial/settings.py: Setup file for Project
tu
Obtain process information from Python and Ubuntu. Basic python tutorial
I want to know the memory usage of the process.
First, you must obtain the system memory information:
Def memory_stat ():
'''
Return the memory info
'''
Mem = {}
Stat = {}
F = open ('/proc/meminfo ')
Lines = f. readlines ()
For line in lines:
If len (line) Name = line. split (':') [0]
Var =
Python tutorial 10-Python anonymous Functions
When you pass in a function, you do not need to explicitly define the function. It is more convenient to directly pass in an anonymous function.
In Python, anonymous functions are provided with limited support. Take the map () function as an example. When f (x) = x * x is
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