Python

When doing data analysis, to a set of analysis, and analysis of the relationship between multiple sets of analysis, then with the traditional cycle of comparison trouble, the collection provides a lot of methods, it is easy to compare the

Common keywordsHow to use keywords commonly used in loopsContinue: End this loop and proceed to the next loopbreak: Jump out of a loop or end a loopCasesLogin with username and password (three chance)Count=0While countUser=input (' Password=input ('

python string Common methodspassword='. jpg 123456789. jpg abcdfg\n' #the value of the string cannot be changed##strip () methodPrint(Password.strip ())#by default, whitespace and line breaks are removed on both sides of the

#define a Python classclassCat:#The Self keyword is equivalent to the this pointer in a C + + class defEat (self):Print("I am eating.") defShow (self):Print("name is%s"%self.name); Tom=Cat () tom.eat ()#add a property to the Tom

# split with multiple whitespace stringsHello = "Hello python hello"Print (A.split (")) # [' Hello ', ' python ', ' ', ' hello ']Print (Hello.split ()) # [' Hello ', ' python ', ' hello ']Print (Len (A.split (") [2]) #" is also a string type data,

‘‘‘Given n non-negative integers represents an elevation map with a width of 1 per bar, calculating how much water can be captured after rain.For exampleGiven [0,1,0,2,1,0,1,3,2,1,2,1], return 6.This problem must first calculate the full water after

defMUL_DIV (exp):#Calculate multiplication whileTrue:ret= Re.search ('[\d\.] +[\*\/]-? [\d\.] +', exp)ifRet:atom_exp=Ret.group () Res=atom_cal (ATOM_EXP) exp=exp.replace (Atom_exp, res)Else: returnFOMAT_EXP (exp)defFOMAT_EXP

Variable hardest HitI. Variables and naming conventions 1.1 What is a variable?As the name implies, the changing amount is variable. Give a chestnut: a = 0. A is a variable, reason: After a assignment of 0, you can re-assign a = 1 a=2 a=3.etc1.2

When using the crawler URL to save, the general will choose set to save Urls,set is a collection, the elements of the collection can not be duplicated, followed by the intersection, and set the function of the collection, the crawler each gets the

Title Description:Flip a linked listHave you ever encountered this problem in a real interview? YesSample ExampleGiven a list of 1->2->3->null, this flipped list is 3->2->1->null challenges One-time rollover complete in situTopic Analysis:One-time

One, for generating and modifying common configuration documents, the name of the current module is changed to Configparser in the python3.x version.Ii. configuration and generation of files1. CodeImport ConfigparserConfig = Configparser.

Data encapsulation, inheritance and polymorphism are the three main characteristics of object-oriented.Data encapsulation:In a class, such as the student class (initialization and name and score two properties), each instance has its own name,score

Pits that may be encountered in the underlying data type:Meta-group:The data type of tuple1= (1) is int, and the data type of tuple2= (' Alex ') is str etc.The data type for tuple1= (1,) and tuple2 is tupleList:Lists and lists can be added together,

1. Python 2.py2, Python Enter, go to the Python compiler, and then execute the commandIn Linux systems:File name:./2.pyInside the file:#!/usr/bin/env pythonPrint (' Hello World ')3. Interpreter Path#！ /usr/bin/env python4. Encoding supports Chinese#-

The dictionary consists of curly braces and key-value pairs, characterized by unordered, key-unique1. Creation of dictionaries#直接创建字典dic1 ={' name ': ' A ', ' Age ': 20}#通过dict创建字典, the output is {' name ': ' A ', ' Age ': 20}dic2=dict ((' Name ', '

one-way linked list -implemented in Pythonnode contains two domain element fields and linked fieldsElement fields are stored in specific dataA linked domain is a store pointing to the next nodeSingle-linked list operation Is_empty () linked

A collection is a Python-unique list of data that can be analyzed by the collection, which is an unordered, unique data type that determines the uniqueness of the list, and the creation of the collection and basic common methods of operation.1,

DefinedAnonymous functions refer to a class of functions or subroutines that do not need to define identifiers. Python uses the lambda syntax to define anonymous functions, with an expression that requires no declaration.The lambda syntax is defined

Tuples are also called read-only lists and cannot be modified by their contents1. Create a tupletuple1= (1,3,2,4,5) tuple2= () #空元组tuple3 = (' A ',) #元组中只有一个元素时要在元素后面加上逗号, otherwise it will be treated as a different data type tuple4= (1, ' a ', [], (

1. anonymous functionAnonymous: No Nameanonymous function: That is, a function without a namePython constructs anonymous functions with lambda expressionsFormat:　　　　Lambda parameter list: expression1 Lambda x:x * * 2 2 3 (Lambda# parentheses Call,