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How to define a function in Python

When defining a function, you need to pay attention to structure, parameters and return values. Python uses def to define functions, such as defgreet():print("Hello,world!"); just pass in parameters when calling, such as greet("Alice"). The parameters can be set to default values, such as defmultiply(a,b=1): returnab; if not specified, the default is 1. Return value output result, otherwise None is returned. It is recommended that the default value of the parameter is used to use immutable objects, and the number of undetermined parameters can be used to use args or **kwargs. The naming should be clear, such as calculate_area, and add it using lowercase letters.

Jul 09, 2025 am 12:47 AM

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How to optimize Python code performance

The key to optimizing Python code performance is to avoid unnecessary loops, use appropriate data structures, utilize built-in functions and third-party libraries, and use cache reasonably and lazy evaluation. 1. Use list comprehension, map() or itertools instead of explicit loops, and directly traverse elements instead of indexes; 2. Select efficient data structures such as set, dict or collections.deque according to the scene, such as using set to improve efficiency when searching frequently; 3. Use built-in functions such as sum(), sorted(), str.join(), etc., and use NumPy and Pandas to process big data; 4. Use @lru_cache to cache the repeated calls and combine it with the generator to achieve lazy

Jul 09, 2025 am 12:42 AM

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Python recursive function example

Recursive functions are methods in Python that can be solved by calling the function itself. It is suitable for scenes such as tree structure traversal, factorial calculation, Fibonacci sequence, etc., such as factorial function shrinks the problem every time until the termination condition n==1 is reached. Note that when using recursion: 1. There must be clear termination conditions; 2. Each recursion must be approached to the termination conditions; 3. Avoid too deep recursion causing RecursionError; 4. Avoid repeated calculations affecting performance. Common applications include directory traversal, nested data analysis and tree structure operation. In fact, it is recommended to first determine the termination conditions, control the depth of recursion, consider the optimization method, and output hierarchical information during debugging to improve efficiency and stability.

Jul 09, 2025 am 12:38 AM

python recursive function

Parsing command line arguments with Python argparse

The argparse module's methods of parsing command line parameters include: 1. Define positional parameters and optional parameters. The positional parameters must be provided. The optional parameters can be used with default values; 2. Use action="store_true" to process boolean switches; 3. Restrict parameter options through choices; 4. Use add_argument_group to group parameters and add descriptions to improve the clarity of help information. For example, parser.add_argument("filename") defines positional parameters, parser.add_argument("--mode",default

Jul 09, 2025 am 12:30 AM

Python JSON dump datetime object

There are three ways to solve the problem of JSON serializing datetime objects in Python: 1. Use the default parameter to define the conversion function to process unrecognized objects, which is suitable for temporary solutions; 2. By inheriting JSONEncoder and rewriting the default method, using the cls parameter to pass it into a custom encoder, which is suitable for unified processing scenarios; 3. Manually convert the datetime field to a string before dumping, which is suitable for data with simple structure. These three methods correspond to different usage scenarios, and you can choose the appropriate method according to your needs.

Jul 09, 2025 am 12:21 AM

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Debugging Python code effectively

Debugging Python code requires mastering three major techniques: 1. Use the built-in pdb module to insert breakpoints into the code for interactive debugging, supporting single-step execution and variable viewing; 2. Make good use of the logging module to replace print, output logs at levels and save files for easy analysis; 3. With the graphical debugging functions of IDEs such as PyCharm and VSCode, it supports visual breakpoints, call stack traces and conditional breakpoint settings, and pay attention to common problems such as variable scope, data reference, floating point accuracy and file paths, and reduce low-level errors with type prompts. These methods can significantly improve debugging efficiency and code quality.

Jul 09, 2025 am 12:11 AM

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What are python iterators?

InPython,iteratorsareobjectsthatallowloopingthroughcollectionsbyimplementing__iter__()and__next__().1)Iteratorsworkviatheiteratorprotocol,using__iter__()toreturntheiteratorand__next__()toretrievethenextitemuntilStopIterationisraised.2)Aniterable(like

Jul 08, 2025 am 02:56 AM

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Understanding Python classmethod vs staticmethod

classmethod is used to receive the class as the first parameter, suitable for factory methods and access class attributes; staticmethod does not receive automatic parameters, and is used as a tool function in the class. 1. Classmethod applicable scenarios include parsing data to generate instances, initializing objects in various ways, accessing or modifying class status; 2. Staticmethod applicable scenarios are tool functions that are independent of the class to improve readability; 3. The key difference is that classmethod can access class attributes and be suitable for inheritance, while staticmethod does not depend on classes or instances.

Jul 08, 2025 am 02:56 AM

What is a context manager in Python?

The context manager is a pattern used in Python to manage resources and can automatically handle the initialization and cleaning of resources. The problem is that manually managing resources can easily lead to errors and leaks, while the context manager ensures that the resources are released correctly through the with statement; 1. Use withopen() to automatically close the file; 2. Customize the __enter__/__exit__ method through the class or the @contextmanager decorator with the contextlib module; 3. Suitable for file operations, database connections, locks and status changes, etc., to improve code security and readability.

Jul 08, 2025 am 02:54 AM

How Python Manages Memory (Garbage Collection)

Pythonmanagesmemoryautomaticallyusingreferencecountingandgenerationalgarbagecollection.1.Referencecountingtracksthenumberofreferencestoeachobject,freeingmemorywhenthecountreacheszero.2.Generationalgarbagecollectionhandlescircularreferencesbyperiodica

Jul 08, 2025 am 02:54 AM

How do you profile Python code performance?

ToprofilePythoncodeperformance,usecProfileforbuilt-inprofiling,timeitforsmallsnippets,andvisualizationtoolslikesnakevizorpy-spy.1)RuncProfileviacommandlineorinsideascripttoidentifyfunctionswithhightottime.2)Usetimeittomeasureandcompareexecutiontimeso

Jul 08, 2025 am 02:53 AM

How to install Python packages with pip

The most common way to install Python packages is to use pip, which is a standard tool for Python. The basic commands include installing the basic package, installing the specified version, upgrading the package, using requirements.txt in batches and solving installation failure problems. The specific operations are as follows: 1. Install the basic package, such as pipinstallrequests; 2. Install the specified version, such as pipinstallpandas==1.4.0; 3. Upgrade package, such as pipinstall-upgradepandas; 4. Use requirements.txt to install in batches, such as pipinstall-rrequirements.txt; 5.

Jul 08, 2025 am 02:52 AM

Exploring Python Mutability and Immutability Concepts

Variable objects (such as lists, dictionaries, and collections) in Python can be modified after creation, while immutable objects (such as integers, floating-point numbers, strings, and tuples) cannot be; for example, string operations will generate new objects, while lists will directly modify the original object; 1. When a function is passed, the mutable objects may have side effects, and modification will affect the outside; 2. The operation of immutable objects is actually rebinding; 3. Although the tuple is immutable, the mutable objects inside it can still be modified. Understanding these differences can help avoid errors and improve code efficiency.

Jul 08, 2025 am 02:52 AM

Making HTTP requests using Python requests library

When using Python's requests library to initiate HTTP requests, you need to pay attention to key points such as parameter passing, exception handling, and session maintenance. 1. The params parameter should be used instead of manually splicing the URL, which can automatically handle encoding and avoid security issues; 2. The POST request selects data (form), json (JSON data) or files (file upload) parameters according to the scenario; 3. Exception handling is recommended to combine response.raise_for_status() and try-except to catch HTTP errors, and set timeout, control redirection and maximum number of retry times; 4. Use Session objects to automatically manage cooks when login is required.

Jul 08, 2025 am 02:51 AM