


Preface
Before talking about the difference between the two operators is and ==, you must first know the three basic elements contained in objects in Python, namely: id (identity), python type() (data type) and value (value). Both is and == are used to compare and judge objects, but the contents of object comparison and judgment are different. Let’s take a look at the specific differences.
There are two methods to compare whether two objects are equal in Python. Simply put, their differences are as follows:
is is to compare whether two references point to the same object (reference comparison).
== is to compare whether two objects are equal.
>>> a = [1, 2, 3] >>> b = a >>> b is a # a的引用复制给b,他们在内存中其实是指向了用一个对象 True >>> b == a # 当然,他们的值也是相等的 True >>> b = a[:] # b通过a切片获得a的部分,这里的切片操作重新分配了对象, >>> b is a # 所以指向的不是同一个对象了 False >>> b == a # 但他们的值还是相等的 Trueimplementation principle
is compares whether the two are the same object, so what is compared is the memory address (whether the id is the same).
== is a value comparison. Immutable objects, such as int, str, will directly compare values. For objects known to Python, their __eq__ function is called for comparison. (In fact, known objects should also be compared through the built-in __eq__ function). For custom objects, if the __eq__ function is implemented, it will be compared. If it is not implemented, the effect is the same as ==.
Object caching mechanism
Python will cache relatively small objects. The next time a relatively small object is used, it will search in the cache area. If it is found, it will not open up new memory, but will continue to cache the address of the small object. Assign new value. Example:
>>> c = 1 >>> d = 1 >>> print(c is d) True >>> 1000 is 10**3 False >>> 1000 == 10**3 True
The assignment is calculated and does not use the buffer area. This can be seen from the first code example.
For strings, you can force the use of the buffer by using the intern function.

Solution to permission issues when viewing Python version in Linux terminal When you try to view Python version in Linux terminal, enter python...

This article explains how to use Beautiful Soup, a Python library, to parse HTML. It details common methods like find(), find_all(), select(), and get_text() for data extraction, handling of diverse HTML structures and errors, and alternatives (Sel

Serialization and deserialization of Python objects are key aspects of any non-trivial program. If you save something to a Python file, you do object serialization and deserialization if you read the configuration file, or if you respond to an HTTP request. In a sense, serialization and deserialization are the most boring things in the world. Who cares about all these formats and protocols? You want to persist or stream some Python objects and retrieve them in full at a later time. This is a great way to see the world on a conceptual level. However, on a practical level, the serialization scheme, format or protocol you choose may determine the speed, security, freedom of maintenance status, and other aspects of the program

This article compares TensorFlow and PyTorch for deep learning. It details the steps involved: data preparation, model building, training, evaluation, and deployment. Key differences between the frameworks, particularly regarding computational grap

Python's statistics module provides powerful data statistical analysis capabilities to help us quickly understand the overall characteristics of data, such as biostatistics and business analysis. Instead of looking at data points one by one, just look at statistics such as mean or variance to discover trends and features in the original data that may be ignored, and compare large datasets more easily and effectively. This tutorial will explain how to calculate the mean and measure the degree of dispersion of the dataset. Unless otherwise stated, all functions in this module support the calculation of the mean() function instead of simply summing the average. Floating point numbers can also be used. import random import statistics from fracti

This tutorial builds upon the previous introduction to Beautiful Soup, focusing on DOM manipulation beyond simple tree navigation. We'll explore efficient search methods and techniques for modifying HTML structure. One common DOM search method is ex

The article discusses popular Python libraries like NumPy, Pandas, Matplotlib, Scikit-learn, TensorFlow, Django, Flask, and Requests, detailing their uses in scientific computing, data analysis, visualization, machine learning, web development, and H

This article guides Python developers on building command-line interfaces (CLIs). It details using libraries like typer, click, and argparse, emphasizing input/output handling, and promoting user-friendly design patterns for improved CLI usability.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

Atom editor mac version download
The most popular open source editor

Dreamweaver Mac version
Visual web development tools

Safe Exam Browser
Safe Exam Browser is a secure browser environment for taking online exams securely. This software turns any computer into a secure workstation. It controls access to any utility and prevents students from using unauthorized resources.

DVWA
Damn Vulnerable Web App (DVWA) is a PHP/MySQL web application that is very vulnerable. Its main goals are to be an aid for security professionals to test their skills and tools in a legal environment, to help web developers better understand the process of securing web applications, and to help teachers/students teach/learn in a classroom environment Web application security. The goal of DVWA is to practice some of the most common web vulnerabilities through a simple and straightforward interface, with varying degrees of difficulty. Please note that this software

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),