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How to schedule recurring tasks in Python?

For simple scripts or tests, use the schedule library because its syntax is simple and easy to read; 2. If persistence and higher reliability are required, choose APScheduler, which supports multiple job storage and cron syntax; 3. When pursuing system-level reliability on Linux/macOS systems, use cron to run Python scripts; 4. When developing web applications or requiring distributed task scheduling, use celery and celery-beat to achieve complex workflows and high scalability; ultimately, select appropriate tools based on environment and reliability requirements. Beginners recommend starting with schedule, and priority is given to APScheduler or celery in the production environment.

Aug 04, 2025 am 07:57 AM

How to implement a thread-safe queue for concurrent programming in Python?

Use queue.Queue is the most reliable method to implement Python thread-safe queues. 1. It has a built-in lock mechanism to avoid race conditions; 2. Put() and get() block by default, and support timeout to avoid infinite waiting; 3. Coordinate task completion with task_done() and join(); 4. Maxsize can be set to implement bounded queues to control memory; 5. Custom encapsulation can provide a clearer interface; 6. Note that queue.Queue is only used for inter-thread communication and is not suitable for multi-process scenarios. If you use join(), task_done() must be called in the consumer, otherwise the program may hang.

Aug 04, 2025 am 07:40 AM

python set difference example

The set difference set operation in Python is used to find elements that exist in one set but not in another set. It can be implemented through the difference() method or the - operator. 1. Use the difference() method: fruits.difference(exotic_fruits) to return the new set {'apple','orange','pear'}; 2. Use the - operator: fruits-exotic_fruits has the same effect and is more concise in writing; 3. Multi-set difference set: set1.difference(set2,set3) or set1-set2-set3 can exclude elements in multiple sets in sequence.

Aug 04, 2025 am 07:22 AM

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python format date string example

In Python, formatting date strings requires the strftime and strptime methods of the datetime module. 1. Use strftime to convert the date object into a string, such as now.strftime("%Y-%m-%d%H:%M:%S") output 2025-08-0414:30:22; 2. Use strptime to parse the string into a date object, and make sure the format is exactly matched, such as datetime.strptime("2025-08-0414:30:22","%Y-%m-%d%H:%M:%S"

Aug 04, 2025 am 07:11 AM

python pdfminer example

First install pdfminer.six, and then select different methods to extract PDF text according to your needs: 1. Use extract_text() to directly extract the full text, which is suitable for plain text PDF; 2. Use extract_pages() to parse page by page, and combine it with LTTextContainer to obtain text blocks and their coordinate information; 4. Use PDFResourceManager and TextConverter to customize the parsing process in advanced scenarios, and support format conversion; it is necessary to note that this library does not support scanned files, complex encoding may lead to garbled code, and it is recommended to cooperate with OCR tools to process picture-type PDF

Aug 04, 2025 am 05:44 AM

python fibonacci sequence example

Generating Fibonacci sequences using loops is the most common and efficient method, suitable for most practical applications; 2. The recursive method is intuitive but has poor performance, and the time complexity is exponentially increasing, and is only suitable for decimal values or teaching purposes; 3. The recursive memory method using the lru_cache decorator significantly improves the recursive performance, suitable for dynamic programming problems that require recursive structures; 4. The generator method is memory efficient, suitable for handling large sequences or streaming data scenarios.

Aug 04, 2025 am 05:40 AM

Building Multi-Tenant Applications with Python Django

The key to implementing multi-tenant Django applications is data isolation and tenant identification. 1. There are three main ways to isolate data: shared table structure (data is distinguished by tenant_id), independent schema (such as PostgreSQLschema) and independent database, each suitable for scenarios of different scales and operation and maintenance capabilities. 2. Tenant identification can be achieved through URL or subdomain name, and the context can be automatically switched in combination with middleware. 3. Using the django-tenants library can simplify the development process, but attention should be paid to database limitations and context settings in asynchronous tasks. 4. Cache and task queues also need to be isolated by tenant, such as using prefixes to distinguish cache keys or passing tenant information in tasks. These are comprehensively considered during the design stage

Aug 04, 2025 am 05:01 AM

django multi-tenant

python fastapi background tasks example

In FastAPI, use BackgroundTasks to perform non-blocking operations after response, such as logging, email sending, etc.; 2. Add multiple tasks through BackgroundTasks.add_task() and execute them in the background in order; 3. If only a single task is needed, you can directly use BackgroundTask to pass; 4. If you actually use emails, you should simulate or integrate SMTP services and call them in the background task; 5. Note that the background task cannot access the closed request context or database connection, and is not suitable for long-term or critical tasks. Special tools such as Celery should be selected; 6. Task functions should be synchronous functions to avoid passing in async functions to prevent event loop problems.

Aug 04, 2025 am 04:51 AM

How to train a decision tree classifier with scikit-learn in Python?

To train a decision tree classifier, first prepare the data and split the training test set, then create the model and train it, then do prediction and evaluation, and finally optionally visualize the tree structure. 1. Prepare the feature matrix X and the target vector y, use built-in data sets such as load_iris, and divide the data with train_test_split; 2. Import DecisionTreeClassifier, initialize the model by setting parameters such as random_state, and train with fit method; 3. Use the predict method to predict the test set, combine accuracy_score and classification_report to evaluate the model performance; 4.

Aug 04, 2025 am 04:42 AM

How to implement a simple caching mechanism using decorators in Python?

The core of implementing cache using decorator is to wrap functions and store their input and output results to avoid repeated calculations; 2. The basic version can be implemented by dictionary, converting parameters into strings as keys, but there is a problem of unlimited memory growth and non-hashable types not supported; 3. It is recommended to use functools.lru_cache decorator, which provides thread-safe, support type parameters and LRU elimination mechanism, suitable for most practical scenarios; 4. If you need custom control, you can implement LRU cache with maximum capacity limit through collections.OrderedDict to manually manage the insertion, access and elimination order of cache items; 5. Cache is suitable for scenarios where input can be hashed and function behavior is pure, which can significantly improve recursion or I

Aug 04, 2025 am 04:35 AM

How to reverse a string in Python?

The most commonly used and most Pythonic method of string inversion is to use slices. 1. Using slice [::-1] is the most recommended method because it is concise, efficient and easy to read; 2. Using ''.join(reversed(text)) is more intuitive and suitable for beginners to understand; 3. Using loops is implemented by pre-character, but due to the immutability of strings, it is not recommended for large strings; 4. Using recursive methods is suitable for teaching demonstrations, but there are call overhead and recursive depth limitations, which are not suitable for long strings. In practical applications, the slice method, namely text[::-1], should be preferred to obtain the best performance and readability.

Aug 04, 2025 am 04:30 AM

How to use the Python interpreter in interactive mode?

TousePython'sinteractivemodeeffectively,startbyopeningtheterminalandtypingpythonorpython3tolaunchtheinterpreter,thenbegincodingatthe>>>prompt.Youcanimmediatelyexecuteexpressionslike2 3orassignvariableslikename="Alice",withresultsdi

Aug 04, 2025 am 04:19 AM

What is the Global Interpreter Lock (GIL) in Python and how does it affect concurrency?

TheGILexiststoensurethreadsafetyinCPythonbyallowingonlyonethreadtoexecutePythonbytecodeatatime,primarilytoprotectreferencecountinginmemorymanagement;1.IthindersparallelisminCPU-boundtasksduetosingle-threadedexecution;2.IthasminimalimpactonI/O-boundta

Aug 04, 2025 am 03:22 AM

Python Pandas Data Cleaning Handbook

Common steps in data cleaning include handling missing values, deduplication data, data type conversion, and processing outliers. When processing missing values, if the missing ratio is small, you can use dropna() to delete it. If you need to keep it, fillna(), such as filling in the mean or mode; when deduplicating data, use drop_duplicates() to delete duplicate rows, or check duplicate columns; data type conversion can be used to ensure the correct format of the numerical and dates; handle outliers can be determined by setting range filtering, IQR method or visualization, such as removing records other than 0 to 120 years.

Aug 04, 2025 am 03:20 AM

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How to schedule recurring tasks in Python?

How to implement a thread-safe queue for concurrent programming in Python?

python set difference example

python format date string example

python pdfminer example

python fibonacci sequence example

Building Multi-Tenant Applications with Python Django

python fastapi background tasks example

How to train a decision tree classifier with scikit-learn in Python?

How to implement a simple caching mechanism using decorators in Python?

How to reverse a string in Python?

How to use the Python interpreter in interactive mode?

What is the Global Interpreter Lock (GIL) in Python and how does it affect concurrency?

Python Pandas Data Cleaning Handbook

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