dict comprehension python 3

DictionaryCharacteristics: No order Go heavy Fast query speed, much faster than the list Consumes more memory than list FunctionNon-fixed parameters:If your function is not sure how many parameters the user wants to pass in the definition, you can use the non-fixed parameterdef stu_register (Name,age,*args): # *args will turn multiple incoming parameters into a tuple form print (Name,age,args) stu_register ("Alex") #输出 #alex () #后面这个 () is args, just because there is

new IO module. Modules such as new, MD5, gopherlib, etc. are removed.Python 2.6 has support for new IO modules.Httplib, Basehttpserver, Cgihttpserver, Simplehttpserver, cookies, Cookielib are incorporated into the HTTP package.The EXEC statement is canceled and only the EXEC () function is left. Python 2.6 already supports the EXEC () function.10. Data typePY 3.x1> removed a long2> added the bytes type, wh

Some of the advanced features of Python:Slice (just like the name, take a whole thing and choose what you want to cut off): by slicing you can quickly remove some elements, as long as you determine the index position, avoid the loop caused by the multi-write codearrays, tuples, and strings can be sliced to get elements, [x:y] to index from index position x to Y position, excluding Y[x:] Start index to end from X, [: Y] from 0 to Y (not including y), [x:y:z]z indicates a number per Z number.Itera

, specified by the value you specify.After turning the country into the default parameter, I moved the position to the last Side.Key parametersUnder normal circumstances, to pass parameters to the function in order, do not want to order the key parameters can be used, just specify the parameter name, But remember a requirement is that the key parameters must be placed after the position parameter. Stu_register (age=22,name= ' Alex ', course= "python"

naturally have the same behavior (methods),#just make sure that all instances of the same class have the same state (attribute)#The simplest and most straightforward way to share properties for all instances is to __dict__ the same dictionary (reference) (Dict)#can see: http://code.activestate.com/recipes/66531/classBorg (object): _state= {} def __new__(CLS, *args, * *kw): OB= Super (Borg, CLS).__new__(CLS, *args, * *kw) ob.__dict__=cls._statere

). W, write-only mode. "unreadable; not exist; create; delete content;" A, append mode. "Readable; not exist" create; "only append content;" "+" means you can read and write a file at the same time r+, can read and write files. "readable; writable; can be added" w+, write and read A +, with a "U" means that the \ r \ n \ r \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ r or r+ mode can be converted automatically when reading RU R+u "B" means processing binary

Chapter 3-String object String object definition:Typedef struct {Pyobject_var_headLong ob_shash;Int ob_sstate;Char ob_sval [1];} Pystringobject;Because the string is a variable-length object, there is a variable-length object header.Ob_shash is used to cache the hash value of the current string, which is useful when querying dict objects whose string is used as the key.Ob_sstate indicates whether the string

,age,args) stu_register ("Alex") #输出 #alex () #后面这个 () is args, just because there is no value, so the empty Stu_register ("Jack", "+", "cn", "Python") #输出 # jack (' cn ', ' Python ')can also have a **kwargsdef stu_register (Name,age,*args,**kwargs): # *kwargs will turn multiple incoming parameters into a dict form print (Name,age,args,kwargs) stu_ Register ("

Using Dict and setIn order to facilitate fast query, Python set up a dictionary, relative to the list, occupy more space, and query speed is also considerable.Storage mode: Key-valuePrinciple:1, dictionary storage when the hash algorithm according to the specified key to calculate the address of value, and put the address in the index2, when the CPU needs to take value,

Python + Selenium notes (3): Use unittest, seleniumunittest # An error may occur when the network is slow. (1) Preface Selenium WebDriver is an API set for automated browser testing. It provides many features for automated interaction with browsers, and these APIs are mainly used to test Web programs. If Selenium WebDriver is used only, we cannot implement the pre-conditions and post-Conditions for executin

a long int i 3 noFour, python2 in print can not add () but 3 to add ()Five, 2 is raw_input equals 3 of input2. Variables: Variables:The results of the operation in the program are charged to the memory for easy follow-up transfer:Cannot start with a number, cannot be a python keyword, and a digital letter underline is

Python learning notes 3-celery distributed task processor, python3-celery Celery is an asynchronous task framework written in python. It has very powerful functions. For details, refer to the official website. Here we mainly provide a demo for you to use this framework quickly. 1. by default, redispip install celeryredis is installed as the carrier of task messag

1. Dictionaries1.1 The difference between a dictionary type and a sequence type:Data is accessed and accessed in different ways.The sequence type is indexed only by numeric type keys (numerically sequentially from the beginning of the sequence);A mapping type can be used as a key for other object types (such as numbers, strings, ganso, usually strings as keys), and the keys of the sequence type are different, and the key of the mapping type is directly or indirectly associated with the stored da

format string/compound field name>>> import humansize>>> si_suffixes = humansize. suffixes[1000]>>> si_suffixes[' KB ', ' MB ', ' GB ', ' TB ', ' PB ', ' EB ', ' ZB ', ' YB ']>>> ' 1000{0[0 '} = 1{0[1]} ' . Format (si_suffixes) ' 1000KB = 1MB '>>> Import humansize>>> Import sys>>> ' 1MB = 1000{0.modules[humansize]. Suffixes[1000][0]} '. Format (SYS) ' 1MB = 1000KB 'Sys.modules is a dictionary that holds imported modules in the current Python instance.

()): Print (INDEX,STR)#生成式#与if语句联合Generatedlist=[x*x forXinchRange1, One)ifX%2==0]print (generatedlist);#两个for联合#能够使用两层循环形成全排列allsortedlist=[(x, y) forXinch ' ABC ' forYinch[1,2,3]]print (Allsortedlist)#列出当前文件夹下全部文件和文件夹名ImportOsdir=[d forDinchOs.listdir ('. ')]print (dir)#字符串变小写#測试strlist=[' ABC ',' dE12 ',334,' 12F ']#strlist =[strs.lower () for STRs in Strlist if Isinstance (STRS,STR)]Strlist=[strs forSTRsinchStrlistif notIsinstance (STRS,STR)orIsinstance (Strs.lower (), str)]print (strlist

Getting started with python crawler-using requests to build zhihu API (3) and pythonrequests Preface In the crawler series, the elegant HTTP library requests describes how to use requests. This time, we use requests to build a zhihu API. The functions include: private Message sending, article thumb ups, user attention, etc., because any function involving user operations must be logged on before the operati

Python 3 Program Development Guide (2nd edition revision)Directory 1 process-oriented programming Quick Start 2 Data Type 3 Combination Type 4 control structures and functions 5 Module 6 OOP 7 file Processing 8 Advanced Programming Techniques 8.1 FP 9 commissioning, testing and profiling Ten Processes and Threads One Net

Django rest_Framework (3) of Python ),Supplement: Why is frontend and backend separation required: A. Because the front-end has its own framework, the efficiency is very high. B. Do not separate the front and back ends. If the company has both clients and apps, you can write them twice. Benefits of the django restful framework: We have written many components, such: A. Authentication: there are classes and

; exec_task_order_overtime order_id=%s'%order_id) Success=BaseHandler.context_services.order_overtime_task_service.process_over_time (order_id)ifSuccess isFalse:logger.error (''%order_id)RaiseReturn (False)Else: Logger.info (''%order_id)exceptException as Exc:logger.info ('exec_task_order_overtime Retry, order_id=%s'%order_id)RaiseSelf.retry (Exc=exc, countdown=3)#try again after 3 seconds, where the countd

#_ *_coding:utf-8_*_#!/usr/bin/env python#取余/diea=10B=3Print (a%3)X=1Y=3Print (x%3)#真正的除法/Print (2/3)#地板除://, the result is an integer (quotient)Print (2//3) #得0#逻辑运算#逻辑与Print (True and False)Print (1 and ') #1的布尔值True, ' The Boolean value is False, so 1 and '---> True and F