python array assignment

) When you assign a value to an object (either as a parameter or as a return value), Python, like Java, always passes a reference to the original object, not a copy. Other languages always pass a copy when assigning values. Python never guesses the user's needs if you want a copy , you must explicitly ask for it. The behavior of Python is simple, fast, and co

Access to:Direct assignment: is actually the object's reference (alias).Shallow copy (copy): Copies the parent object and does not copy the inner sub-object of the object.Deep Copy (deepcopy): The Deepcopy method of the Copy module, which completely copies the parent object and its child objects.Direct code, at a glanceExample of a shallow copy of a dictionary>>>a = {1: [+/-]}>>> B = a.copy ()>>> A, b({1: [1, 2, 3]}, {1: [1, 2, 3]})>>> A[1].append (4)

# Direct assignment, after which the variable is applied to the same ID () address, and subsequent modifications will be used to drink also modifiednum1=[1,2,3,4]Num2=num1Print (ID (NUM1))Print (ID (num2))num2[0]=111Print (NUM1)Print (NUM2)#深拷贝 completely open up new space, modify the value after copy, the value will not be affectedImport Copynum1=[1,2,3,4]Num2=copy.deepcopy (NUM1)Print (NUM1,NUM2)Print (ID (NUM1))Print (ID (num2))num2[0]=111Print (NU

This article brings you a brief introduction to the assignment shallow copy deep copy of Python (example), has certain reference value, the friend who needs can refer to, hope to be helpful to you. When writing the dict data type, there are references to the "assignment statement" and the copy () function.In fact, when it comes to shading, you need to consider

In Python, when we make a variable equal to another variable, it does not pass the value to it, but instead directly changes the address to the point. We want to see the address of a variable in memory, which can be viewed by ID (variable). Let's take a look at this interesting process through a small example. >>> x = 12>>> y= 13>>> ID (x) 1865402384>>> ID (y) 1865402416>>> x = y>> Gt ID (x) 1865402416>>> ID (y) 1865402416 The first

Python learning notes enumerate () and range (len) usage and assignment subtotal, pythonenumerate #! /Uer/bin/env python # _ * _ coding: UTF-8 _ * _ # format 1a = 'abc' for I in range (len ()): print a [I], '(% d)' % I A (0)B (1)C (2) # Format 2for A, I in enumerate ('abc'): print I, A 0B 1C 2 # Format 2.1b = raw_input ('wartyouname: ') for I, j in enumerate

, with large amounts of data, it is cumbersome to execute code so that it is time to store two of data in a variable, such as:studentnumber = "CoXie01"If you look at this variable name, a lot of people are looking at the face of the crazy, what is this big string of things? In the strict code, generally encountered this situation, the following two kinds of naming methods are used:underline naming method :Take the above as an example:student_number = "CoXie01"Obviously you can see, student and n

This article mainly introduces the value assignment operator in Python, which is a basic skill in Python. if you need it, refer to the following table to list the value assignment operators supported by all Python languages. Assume that variable a holds 10 and variable B hol

where?When executing a python program, report this error.Why?Variable scope problems, variables defined in the branch can be correctly obtained when the condition is met, and the error is reported when the condition is not met.The same?Pull the variable from the branch to the branch, or define the variable in another branch, so that it is defined all the time to the accessError codedef show_error (number): # When this condition is satisfied, result

Python dict dictionary and some examples of value assignment reference (detailed description), pythondict Recently, I am working on a very large database that needs to be searched by numerical value. So I thought of the dictionary in python, and I have never used dict. List and tuple are the most commonly used) I have read the following method to create a diction

": { 'People's square': { 'Fried Chicken Shop': {}, }, }, 'Zhabei': { 'train station': { 'Ctrip': {}, }, }, 'Pudong': {}, }, 'Shandong': {},}exit_flag=False while notExit_flag: forIinchData:Print(i)#into the dead loop .Choice= Input ("your option >>>:") ifChoiceinchData: while notExit_flag: forJinchData[choice]:Print("\ t", j) Choice2= Input ('your 2nd option >>>:') while

There are three ways to assign a Python variable;1. Direct assignment: Age = 282. Multiple variable assignment age, sex = 1 #每个变量都必须要有个对应的值3. Special form Assignment A = b = 28Note that variables must be assigned before they are used, which differs from C + + because there is no type modifier in front of the

)Print(' Lst1: ' + Str(LST1)+ '; ID: ' + Str(ID(LST1)))Print(' Lst2: ' + Str(LST2)+ '; ID: ' + Str(ID(LST2))) Lst2.pop ()Print(' Lst1: ' + Str(LST1)+ '; ID: ' + Str(ID(LST1)))Print(' Lst2: ' + Str(LST2)+ '; ID: ' + Str(ID(LST2)))First, create a list object Lst1, and let both Lst2 and Lst1 point to the same list. The following append operations and pop operations, whether for Lst1 or lst2, are in fact the same list. Two variables all point to the same list, the action on either variable will affe

new employee record , with the phone to do a unique key, staff_id need to increase solution : Use phone number as the unique key, that is, the format in which the main dictionary is created in JSON is: {1390000000: {' name ': ' May Lol ', ' age ': All, ' staff_id ': xxxxxx, ' Enroll_date ': xxxxxxxx}} staff_id self-increment, need to build in an ordered dictionary, import collection module, collections. Ordereddict ④ can delete specified employee information record, enter empl

, you bastard, write a bunch of things we all know. Come on, I want a refund. Then I'm here to say that the refund is not back AH.How to write a good variable?Let me cite one more example:x = "CoXieQqun"y = "725479218"z = x + y print(z)The result of the operation is:CoXieQqun725479218I don't know if you can read it, look at the variable and the value of the variable, if you don't look at the value of the variable, such as:xxx = "CoXieQqun"xxx = "725479218"Do you know what a variable is?As y

1. Assigning values to variablesLetters are quoted as strings, not labeled as variable names." Jbzhang " = nameprint="jbz"print(name2)Memory Reclamation: The memory space created, when there is no variable pointing, the memory space will be emptied or deleted directly.Like what:1. Delete directlyAge=21Del age2. Cancel the pointAge=22Age=232.if Statement Implementation guess ageAge_of_princal= + = Int (input (">>:"))if guess_age = = age_of_princal: Print ("yes,you got it. " Else: print("n

: Assignment is to assign the address of an object to a variable, so that the variable points to that address (old bottles of old wine). A shallow copy creates a new variable or container in another address, but the address of the element within the container is a copy of the address of the element of the source object. This means that the new container points to the old element (new bottle of old wine). A deep copy is a new variable

Yesterday I want to do a Python function in the number of send statistics, need to use global variables, as follows1COUNT =02 3 defsendonelinemsg (producer, listfromline):4Acsnstr =Listfromline[0]5Macstr = listfromline[1]6Onlinetimestr = listfromline[2]7msg = {'Clientmac': Macstr,'ACSN': Acsnstr,'Onlinetime': Onlinetimestr}8MSGSTR =json.dumps (msg)9 producer.produce (MSGSTR)TenCOUNT + = 1The error is reported, and the workaround is to add a row to the

The python empty dictionary list has different effects on the assignment. Recently, Naive Bayes has encountered an interesting phenomenon (based on Python3.6.3) I generate a list composed of 10 empty dictionaries: FirstGeneration Method (most people may use this method, which is simple) > A = [{}] * 10 However, a problem occurs when assigning values to the dictionary in. > A [3] [3] = 32 > [{3: 32 },{3: 32

#-*-Coding:utf-8-*-#Author David"""Feature Description: Write the Login interfaceEnter user name and passwordShow welcome message after successful authenticationThree-time error after locking"""#用户信息表user = "David"passwd = "123456"unlock = 1Error_count = 0"""defining function bodiesFunction Description:1) When the user enters the user name, the first to determine whether the existence, if there is the next judgment, if not present, prompt for the user name.2) When the user name exists, the syste