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Content:

Section 1. Understanding Libraries, Packages, and Modules

Section 2. Python Standard Library

Section 3. Third-Party Libraries and pip

Section 4. Practical Application - Weather Reporter

Section 5. Practical Application - File Backup Helper

Section 1. Understanding Libraries, Packages, and Modules

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1.1. Core Concepts

Library

Focusing on the function
May include multiple packages and modules
Collection of reusable code

Package

A folder containing multiple modules
Organizes related modules together

Module

A single .py file
Contains functions, classes, and variables
Basic unit of code organization

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1.2. Python Standard Library

Pre-installed Tools

Comes with every Python installation
No additional installation required
Examples: math, random, datetime, os

Basic Usage Example

import math
print("Pi is approximately " + str(math.pi))
print("Square root of 16: " + str(math.sqrt(16)))

Discovering Available Modules

help('modules')

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1.3. Three Import Methods

Method 1: Full Import

Get the whole toolbox:

import math
print("2^5 = " + str(math.pow(2, 5)))

Method 2: Specific Import

Grab just what you need:

from random import randint
print("Random dice roll: " + str(randint(1, 6)))

Method 3: Alias Import

Make it short:

import pandas as pd
data = {'Birds': ['Eagle', 'Penguin'], 'Speed': [320, 8]}
df = pd.DataFrame(data)
print(df)

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1.4. Import Method Comparison

Why Different Import Methods?

Method	Advantage	Use Case
Full Import	Prevents name conflicts	Large libraries, avoid namespace pollution
Specific Import	Cleaner code, less typing	Only need 1-2 functions from module
Alias Import	Saves typing long names	Frequently used libraries like pandas/numpy

Mixed Import Styles

Combine different approaches:

from math import sqrt as sq
print("Square root of 121: " + str(sq(121)))

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Section 2. Python Standard Library

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2.1. Core Standard Library Modules

Essential Modules

math - Mathematical functions
time - Time-related functions
random - Random number generation
os - Operating system interface
datetime - Date and time manipulation
shutil - High-level file operations

Learn to use “help()” for self-study.

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2.2. datetime Module

Current Time

import datetime

now = datetime.datetime.now()
print("Current time: " + str(now))

Output format: Year/Month/Day Hour:Minute:Second.Microsecond

Time Calculation with timedelta

future_date = now + datetime.timedelta(days=3)
print("Date after 3 days: " + str(future_date.date()))

timedelta Parameters

days
hours
minutes
seconds
weeks

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Section 3. Third-Party Libraries and pip

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3.1. Introduction to Third-Party Libraries

What are Third-Party Libraries?

Extra tools you can download
Massive collection at PyPI.org
Extend Python’s capabilities

Popular Examples

pandas - Data manipulation and analysis
requests - HTTP library for web communication
numpy - Numerical computing

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3.2. pip Package Manager

Checking pip Version

$ pip3 --version
pip 24.0 from ... (python 3.7)

Key Features

Built-in tool for package management
Comes with Python 3.4+
Main commands: install, uninstall, list

Installing Packages

$ pip3 install requests
Collecting requests...
Successfully installed requests-2.31.0

Listing Installed Packages

$ pip3 list
Package    Version
---------- -------
pip        21.2.4
requests   2.31.0
setuptools 57.4.0

pip3 freeze

pip3 install requests==2.31.0

pip3 show requests

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3.3. Package Installation Optimization

Using Mirrors for Speed

$ pip3 install -i https://pypi.tuna.tsinghua.edu.cn/simple pandas

Popular Mirrors

Tsinghua University
AliCloud
University of Science and Technology of China

Permanent Mirror Configuration

$ pip3 config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple

Creates ~/.config/pip/pip.conf file

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3.4. Using requests Library

Basic GET Request

import requests

response = requests.get("https://www.baidu.com")
print("Status Code: " + str(response.status_code))
print("Response Text: " + response.text[:100] + "...")

Real-World Weather Example

import requests

city = "Beijing"
url = "http://wttr.in/" + city + "?format=3"
response = requests.get(url)
print("Weather in " + city + ": " + response.text)

Upgrading Packages

$ pip3 install --upgrade requests
$ pip3 install requests==2.31.0

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Section 4. Practical Application - Weather Reporter

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4.1. Project Overview

Goal

Combine web data fetching and time handling to create a weather reporting tool.

Required Libraries

requests - Fetch weather data from websites
datetime - Handle current time display

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4.2. Time Display Function

Current Time Formatting

import datetime

current_time = datetime.datetime.now()
formatted_time = current_time.strftime("%H:%M")
print("Hello! It's " + formatted_time + " now!")

Time Zone Consideration

When using datetime, be aware of your system’s time zone settings. The example uses local system time.

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4.3. Weather Data Function

Fetching Weather Data

import requests

def get_weather(city):
    url = "http://wttr.in/" + city + "?format=%t+%C"
    response = requests.get(url)
    return response.text

print(get_weather("London"))

API Format Options

%t - Temperature
%C - Weather condition
%h - Humidity
%w - Wind speed

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4.4. Complete Weather Reporter

Combined Function

import datetime
import requests

def get_weather(city):
    url = "http://wttr.in/" + city + "?format=%t+%C"
    response = requests.get(url)
    return response.text

def weather_report(city):
    time_now = datetime.datetime.now().strftime("%H:%M")
    weather = get_weather(city)
    return "[" + time_now + "] Weather in " + city + ": " + weather

print(weather_report("NewYork"))

Potential Issues

If you are in Beijing but checking New York weather, the time displayed will be Beijing Time, not local New York time.

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Section 5. Practical Application - File Backup Helper

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5.1. Project Overview

Goal

Automate file copying operations for backup purposes.

Required Libraries

os - Handle file paths and directory operations
shutil - High-level file operations (copy, move, etc.)

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5.2. Directory Management

Checking and Creating Directories

import os

my_folder = "documents"
if not os.path.exists(my_folder):
    os.makedirs(my_folder)
    print("Created " + my_folder + "!")

Path Operations

# Join path components
full_path = os.path.join("backup", "file.txt")
print(full_path)

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5.3. File Backup Script

Copying Specific File Types

import os
import shutil

def backup_files(src_folder, dst_folder):
    # Create destination if it doesn't exist
    if not os.path.exists(dst_folder):
        os.makedirs(dst_folder)
    
    # Copy all .txt files
    for file in os.listdir(src_folder):
        if file.endswith(".txt"):
            src_path = os.path.join(src_folder, file)
            dst_path = os.path.join(dst_folder, file)
            shutil.copy2(src_path, dst_path)
            print("Copied " + file + "!")

# Usage example
backup_files("notes", "backup")

shutil.copy2() vs shutil.copy()

copy2() - Preserves metadata (timestamps, permissions)
copy() - Only copies file content

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Pro Tip: Explore Libraries!

Standard library documentation: docs.python.org/3/library
PyPI for new discoveries: pypi.org
Remember: Great programmers stand on the shoulders of giants 🏗

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