Python

Python arithmetic operatorsThe following hypothetical variables: a=10,b=20: operator Description Example + Add-Two objects added A + B output result 30 - Minus-get negative

>>> with open ("Login.txt", "r+", ending= "Utf-8") as F:... f.readline ()File "", Line 2 f.readline () ^ indentationerror:expected an indented blockCause: No indentation, add a space or tab to a new lineWith open ("Users_info", "RW", encoding= "Utf-8

First1. Nested invocation of function: Other functions are called in the process of calling the function. The code is simple and readable.Example 1:def foo ():Print (' from foo ')def bar ():Print (' from Bar ')Foo ()Bar ()#结果:From Barfrom FooExample

1.yield meaning of production and generation, the function with yield in Python is called the Generator (Generator)The larger the #生成10000个元素的List value of the ' for I in range ', the larger the memory consumed in the run will be 10000 for J in

There are three forms of time in Python:float,struct tuple (Time.struct_time or Datetime.datetime),StrCommonly used for:float -to- struct tuple: time. localtime (float)struct Time tuple --and str: Time. strftime (format, struct time tuple)Str --

#!/usr/bin/env Python3#-*-coding:utf-8-*- fromSeleniumImportWebdriver fromSelenium.webdriver.common.action_chainsImportActionchainsImport TimeclassLogintest (object):def __init__(self): Self.url="'Self.uname="'self.pwd="'Self.userele="'Self.pwdele="'

Company RABBITMQ Consumer Reconnect after the old connection will not be disconnected, will always exist in the service side, as for what is not yet found. This causes the number of connections each time after a lot of increase, so write a Python

The OS module operates as follows:1OS.GETCWD ()#gets the current working directory, which is the directory path of the current Python script work2Os.chdir ("dirname")#change the current script working directory, equivalent to the shell

CODE:#!/usr/bin/python #-*-Coding:utf-8-*-"Created on 2014-8-19@author:guaguastd@name:job_title_standard.py" ' Import Osimport csvfrom Collections Import counterfrom operator import itemgetterfrom prettytable import prettytable# Specify CSV

First, the module1. Standard libraryNo need to install, directly into the module used.Import SYS module:Import Sysprint (Sys.path) #打印环境变量绝对路径print (SYS.ARGV) #打印当前脚本相对路径Print a script The second parameter: print (SYS.ARGV [2])Import OS

The purpose of the ricequant quantification community is to allow those who are interested in quantifying to collide and learn useful and practical quantitative knowledge in sharing and arguing.Depending on your contribution to the community and the

1. Sync Lock (Lock)Data disturbances occur when individual threads need access to a common resourceFor example:1 Import Threading,time2 def Sub ():3 GlobalNum #对全局变量进行操作4 5temp=Num6Time.sleep (0.001) #模拟线程执行中出现I/o delay,

Dictionary type ****************** Why do I need a dictionary type?>>> list1 = ["Name", "Age", "gender"]>>> list2 = ["Fentiao", 5, "male"]>>> Zip (list1, List2)Combine two lists with a zip built-in function, help (Zip)[(' Name ', ' Fentiao '), ('

I've been learning about asynchronous programming in Python, and after reading some blogs, I've done some quizzes: comparing the differences in efficiency between asyncio+aiohttp crawlers and asyncio+aiohttp+concurrent.futures (thread pool/process

1, the number type simple introduction The number types in Python include: Integer, Long, Boolean, double-precision floating-point, decimal floating-point, plural. These numeric types are immutable types. That is, changing the value of a

Learning python following Liaoche's blog, and seeing the generator chapter, first mentions Generator, yield, and then in the search for information, and found the concept of the co-process, this article summarizes these concepts. 　　generator ,

Dictionaries and collections in Python Mapping Type: represents a collection of arbitrary objects, and can be indexed and serialized differently by another collection of almost any key value, which is unordered and indexed by key any

The Beautiful Soup Standard library is a Python library that extracts data from Html/xml files, allows you to navigate through your favorite converters, find and modify documents, and Beautiful soup will save hours of working time. The Pymongo

Anaconda is a Python release for scientific computing that supports Linux, MAC, Windows, and Python packages that contain a number of popular scientific calculations and data analysis. The most tedious of Python learning is the management of

Class Origin and metaclass, origin metaclassI. Overview We know that classes can be used as instances to produce objects. How is the class itself produced? Let's trace the origin of the class.Ii. Class Origin 2.1 create a class Class Foo (object):