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python selenium wait for element example

Using WebDriverWait with expected_conditions is the best practice to wait for elements to appear, and can effectively avoid errors caused by slow page loading. 1. It is recommended to use WebDriverWait(driver,10).until(EC.element_to_be_clickable((By.ID,"login-btn"))) to wait for the element to be clicked; 2. Common conditions include: EC.presence_of_element_located to check whether the element exists in the DOM, EC.visibility_of_element_loca

Jul 29, 2025 am 02:56 AM

python flask middleware example

Use Flask's before_request and after_request hooks to simulate middleware functions, suitable for in-app logic such as logging, performance monitoring and authentication; 2. Lower-level control can be achieved through WSGI middleware, such as modifying environment and response headers, suitable for cross-frame reuse or plug-in design; 3. The JWT authentication example shows how to perform permission verification before requesting and inject user information, and pass data in combination with g objects. Summary: Most scenarios recommend using the Flask hook function, because it is simple and efficient. WSGI middleware is only selected when the underlying WSGI control is needed. The combination of the two can flexibly implement various middleware requirements.

Jul 29, 2025 am 02:54 AM

python django signals example

First create a Profile model, including one-to-one association with User and profile fields; 2. Use the post_save signal to automatically create a Profile when the user creates, and save the associated Profile when the user updates; 3. Import the signals module in the ready() method of apps.py to register the signal; 4. Ensure that the application has been added to the INSTALLED_APPS of settings. 5. Test and verify whether the Profile is automatically generated after the user creates. This mechanism realizes the function of automatically creating personal information after user registration, effectively decoupling business logic, avoiding manual calls, and improving code maintainability.

Jul 29, 2025 am 02:53 AM

python turtle graphics example

The answer is to use Python's turtle module to draw color-rotated square patterns, 1. Set the screen background to black and create a brush, 2. Define a list of red, yellow, blue, green, purple, and orange colors, 3. Draw a square each time through 90 cycles and turn right 4 degrees, 4. Use a different color each time and finally form a flower-like pattern, 5. Click the window to exit the program, and after the complete code is run, a circular pattern composed of color-rotated squares will be displayed.

Jul 29, 2025 am 02:50 AM

Smart Contract Development with Python

Python programmers can participate in smart contract development through the following paths: 1. Use Vyper to write contracts, its syntax is close to Python, and is suitable for Ethereum development. Examples include initialization and setting greetings functions; 2. Use Brownie framework for contract deployment and testing, support Solidity/Vyper contracts and provide Pythonized processes; 3. Use web3.py to interact with Ethereum nodes to realize off-chain data reading, transaction sending, event listening and other functions. The three together form a complete Pythonized development solution.

Jul 29, 2025 am 02:50 AM

Feature Engineering with Python

Feature engineering is a combination of data preprocessing and feature construction, with the goal of converting the original data into a form that is easier to understand in the model. Because the original data often contains problems such as noise, missing values, inconsistent formats, direct input to the model is not effective. Common operations include: 1. Missing value processing, such as filling with SimpleImputer or fillna(); 2. Category encoding, such as binary variable mapping to 0/1, and multiple categories use One-Hot or TargetEncoding; 3. Standardization and normalization, such as StandardScaler or MinMaxScaler; 4. Box processing, such as age segmentation and income interval discretization. More meaningful feature structures need to be combined with business understanding, such as e-commerce scenarios

Jul 29, 2025 am 02:43 AM

python feature engineering

python random number example

Random.randint(a,b) generates random integers containing a and b, random.randrange(a,b,step) generates random integers starting from a, not including b, and can set a step size; 2.random.random() generates random floating point numbers between [0.0, 1.0), random.uniform(a,b) generates random floating point numbers in the interval [a,b]; 3.random.choice(seq) randomly selects an element from the sequence, random.choices(seq,k=n) can repeatedly select n, random.sample(seq,k=n) does not repeat; 4.

Jul 29, 2025 am 02:42 AM

programming language

python setattr example

setattr() is a built-in function in Python for dynamically setting object properties. Its basic syntax is setattr(object, name, value). 1. It can be used to add new attributes to the object, such as adding age attributes to Person instances; 2. It can modify existing attribute values, such as changing name from "Alice" to "Bob"; 3. It can set properties in batches in combination with dictionaries, which is suitable for processing configuration or JSON data; 4. It can dynamically add class attributes or methods on the class, such as adding version and get_info for MyClass; 5. When using it, you need to pay attention to the legality of the attribute name to avoid using the point that cannot be passed.

Jul 29, 2025 am 02:40 AM

python os.walk example

os.walk() is a tool in Python for recursively traversing directory trees, returning (dirpath, dirnames, filenames) triplets; 1. It can be used to traverse all files and subdirectories; 2. Finding specific types of files requires filtering in combination with endswith(); 3. Calculate the number and size of files and cumulative file information; 4. Skip some directories and modify the dirnames list in situ; 5. Only traverse one layer of available break to end the loop; this method has the default depth priority, and the path separator is automatically adapted to the system, suitable for file scanning, backup and other tasks.

Jul 29, 2025 am 02:36 AM

Penetration Testing with Python Scapy

Common uses of Scapy in penetration testing include network scanning, packet sniffing, constructing custom protocol packages, and assisting man-in-the-middle attacks. 1. In terms of network scanning, Scapy can realize ARP scanning to discover active hosts and TCPSYN scanning to identify open ports; 2. Packet sniffing can capture and analyze traffic through the sniff function, which is suitable for monitoring sensitive information transmitted in plain text; 3. Constructing custom packets can simulate attack behavior, such as forging source addresses to send UDP packets; 4. In a man-in-the-middle attack, Scapy can initiate ARP spoofing and misleading the target to send traffic to the attacker's device.

Jul 29, 2025 am 02:35 AM

Container Orchestration for Python Applications

The container orchestration for deploying Python applications is actually not complicated. The core is to make the container run stably and collaborate well. The first step is to package the application into a Docker image, write Dockerfile installation dependencies, copy code, and set up startup commands. Then choose the right orchestration tool. Kubernetes is the mainstream solution, suitable for multi-service scenarios, while DockerCompose, Nomad or AWS's ECS/Fargate is more suitable for lightweight or stand-alone deployments. In terms of configuration management, it is recommended to split the configuration files by environment and use ConfigMap and Secret to separate non-sensitive and sensitive information. Communication between services should be completed through internal service names to avoid exposing public IP

Jul 29, 2025 am 02:33 AM

python memoryview example

memoryview is a built-in type in Python for directly accessing memory data of objects that support buffering protocols, avoiding replication and improving performance. 1. Create memoryview such as mv=memoryview(bytearray(b'HelloWorld')), and you can slice and access such as mv[:5].tobytes() to get b'Hello' without copying data; 2. You can modify the original object, such as mv[0]=ord('h') to make the original bytearray become b'helloWorld'; 3. Efficiently process large arrays, such as memoryview(bytearray(10_000_000))[1000:200

Jul 29, 2025 am 02:32 AM

python numpy reshape example

numpy.reshape() is used to change the shape of the array without changing the data. 1. Basic operations are such as converting a one-dimensional array of 6 elements into (2,3) two-dimensional array; 2. Use -1 to automatically infer dimensions, such as reshape(2,-1) or reshape(-1,4); 3. Multi-dimensional conversion can be performed, such as converting a one-dimensional array of 24 elements into a three-dimensional array of (2,3,4); 4. Use reshape(-1) to efficiently flatten the array into one-dimensional; 5. Reshape does not modify the original array, return the new array, and the original array remains unchanged; note that the total number of new and old shape elements must be consistent, otherwise an error will be reported.

Jul 29, 2025 am 02:24 AM

php java programming

python iter and next example

iter() is used to obtain the iterator object, and next() is used to obtain the next element; 1. Use iterator() to convert iterable objects such as lists into iterators; 2. Call next() to obtain elements one by one, and trigger StopIteration exception when the elements are exhausted; 3. Use next(iterator, default) to avoid exceptions; 4. Custom iterators need to implement the __iter__() and __next__() methods to control iteration logic; using default values is a common way to safe traversal, and the entire mechanism is concise and practical.

Jul 29, 2025 am 02:20 AM

python Iterator