Python

Python does not have a character type that is a single character or string length of 1Once a string is defined, it cannot be modified>>> str1 = ' I love junjie.com '>>> Str1[:6]' I love '>>> str1' I Love junjie.com '>>> str1[5] substringE>>> Str1[:6]

#-*-coding:utf-8-*-Importurllib.requestImportSocketImportReImportSYSImportOS Imaggetpath="G:\\zxh_python\\spider\\imagesdown"defsaveFile (path):if notOs.path.isdir (Imaggetpath): Os.mkdir (Imaggetpath) POS= Path.rindex ('/') T= Os.path.join

A brief history of character coding:United States: 1963 ASCII (contains 127 characters of 1 bytes)China: 1980 GB2312 (contains 7,445 characters, including 6,763 Kanji and 682 other symbols)1993 GB13000 (20,902 characters included)1995 GBK1.0 (21,003

How the Python library is installed1, custom installation of Python library--Find the appropriate website, download and installExample: Pywin32 Library installation. exe, directly double-click to automatically identify the installation

Python's multiprocessing has two ways of creating processes, each of which is not the same as the recycling of the process resources, and the following are for the Process,pool and the system's own fork three process analysis.1. Way One: fork

First analyze the slice operation from the principle:The list of slices, inside is called the __getitem__,__setitem__,__delitem__ and slice functions. The slice function is also associated with the range () function.The key passed to the slice is a

Strict parsing: There are symbols except numbers or letters (spaces, semicolons, etc) will be falseIsalnum () must be a mix of numbers and lettersIsalpha () is case insensitivestr_1 ="123"str_2="ABC"str_3="123ABC"#Use the IsDigit function to

#Coding:utf-8ImportSocketdefUrl2ip (): forOneurlinchurllist.readlines (): URL=str (Oneurl.strip ()) [7:] Print(URL)Try: IP=socket.gethostbyname (URL)Print(IP) iplist.writelines (str (IP)+"\ n") except: Print("This URL 2 IP

ReflectionThere are 4 ways to map or modify the state, properties, and methods of a program when it is runSmall example--call methods based on user input:Class Dog (object): def __init__ (self,name): self.name = name def eat (self):

############################################################################# #center (self, width, fillchar=None) Content centered, Width: total length; Fillchar: padding content in white space, default no = ' Eason ' B = a.center (' # ') print (b)

ImportThreading#To create a global threadlocal object:Local_school =threading.local ()defprocess_student ():#gets the student associated with the current thread:std =local_school.studentPrint('Hello,%s (in%s)'%(Std, Threading.current_thread (). Name)

Recursive algorithm1. Definition of recursionRecursion, which is a subroutine (or function) that calls itself directly or indirectly through a series of invocation statements, is a basic way to describe the problem and solve the problem.Recursive

Python topic-Mysql database (python3. _ + PyMysql),-mysqlpymysql I have previously written a blog about using the MySQL database in Python, mainly using the Python2 and MySQLdb drivers.Use mysql Databases in python Python2 ---> Python3 MySQLdb -->

Chapter 1 of machine learning practicesChapter 2 machine learning basics Machine Learning Overview Machine LearningIt is to convert unordered data into useful information. We will use computers to demonstrate the true meaning behind the data.Machine

Basics of automated testing-Introduction to Selenium and basics-selenium1. General process of software development 2. What is software testing? Software Testing describes a process used to validate the correctness, integrity, security, and quality

Python virtual environment: virtualenv, pythonvirtualenvVirtualenv Virtualenv is used to create an independent Python environment. Multiple Python environments are independent of each other and do not affect each other. It can:1. Install the new

Learn Regular Expression notes, regular expression notes1. Introduction to Regular Expressions Regular Expressions provide the basis for advanced text pattern matching, extraction, and or form searching and replacement. That is to say, if the

Python's white loop and pythonwhite Loop # _ * _ Coding: UTF-8 _*_Import datetimeName = 'gyf'Passd = 123.Count = 0Now = datetime. datetime. now ()While count Username = input ("you name is :")Password = int (input ("you password get my. it. s

Matplotlib and matplotlib Legend reference: http://matplotlib.org/gallery.html   API reference: http://matplotlib.org/api/pyplot_summary.html   #-*-Coding: UTF-8-*-"" Simple demo with multiple subplots. "import numpy as npimport matplotlib.

Python coroutine and python coroutine If Python books have a certain guiding role, the (coroutine is) Documentation lacks the least-known Python features, so it seems to be the most useless feature on the surface.