Introduction to PSL Library

The PSL (Python Standard Library) is a collection of modules and functions that come pre-installed with Python, offering a wide range of functionalities. Whether you’re a beginner or an experienced developer, the PSL can be a powerful tool in your development arsenal. In this article, we will explore some of the most useful APIs within the PSL and provide code snippets to demonstrate their use.

API Examples

1. Datetime Module

The datetime module supplies classes for manipulating dates and times.

from datetime import datetime, timedelta

# Get the current date and time
now = datetime.now()
print("Current Date and Time:", now)

# Create a timedelta object to represent a duration
delta = timedelta(days=7)
print("7 Days from Now:", now + delta)

2. Math Module

The math module provides access to mathematical functions.

import math

# Calculate square root
print("Square Root of 16:", math.sqrt(16))

# Calculate the cosine of an angle in radians
print("Cosine of 0:", math.cos(0))

3. JSON Module

The json module is used to parse JSON. It can also be used to convert Python objects into JSON strings.

import json

# Creating a JSON string
person = {"name": "Alice", "age": 25}
person_json = json.dumps(person)
print("JSON String:", person_json)

# Parsing a JSON string
person_dict = json.loads(person_json)
print("Parsed JSON:", person_dict)

4. OS Module

The os module provides a way to interact with the operating system.

import os

# Get the current working directory
cwd = os.getcwd()
print("Current Working Directory:", cwd)

# Listing files and directories
print("List of Files and Directories:", os.listdir('.'))

5. Random Module

The random module is used to generate random numbers.

import random

# Generate a random integer between 0 and 10
print("Random Integer:", random.randint(0, 10))

# Choose a random element from a list
elements = ['apple', 'banana', 'cherry']
print("Random Choice:", random.choice(elements))

App Example

Now, let’s create a simple application that utilizes some of the APIs mentioned above.

from datetime import datetime
import json
import os
import random

def log_event(event):
    log = {
        'timestamp': str(datetime.now()),
        'event': event
    }
    with open('log.txt', 'a') as file:
        file.write(json.dumps(log) + '\n')

def main():
    # Log the start of the app
    log_event("Application started")
    
    # Randomly select an action
    actions = ['Action A', 'Action B', 'Action C']
    selected_action = random.choice(actions)
    log_event("Selected Action: " + selected_action)
    
    # Log the end of the app
    log_event("Application ended")
    
    # Display log
    with open('log.txt', 'r') as file:
        for line in file:
            print(json.loads(line))

if __name__ == "__main__":
    main()

In this simple app, we log events with timestamps, use random.choice to select actions, and read from and write to a log file. The PSL modules make it easy to handle common tasks with minimal code.

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