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Content:

Section 1. Introduction to Function & Module

Section 2. Function Basic Syntax

Section 3. Advanced Parameters & Return Values

Section 4. Python Modules System

Section 5. Practical Python Examples for Beginners

Section 1. Introduction to Function & Module

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1.1. Functions: Like a Microwave Preset Button

Real-life analogy:

Preset buttons = Predefined functions
“Popcorn” button = def popcorn_mode()
“Beverage” button = def reheat_drink()

Python example:

def start_microwave(preset):
    if preset == "popcorn":
        print('heat for 180 seconds')
    elif preset == "beverage":
        print('heat for 45 seconds')

start_microwave("popcorn")

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1.2. Why do We Need Functions

Problem without functions:

# Making 3 sandwiches
print("1. Get bread")
print("2. Add filling")
print("3. Close sandwich")
print("------")
print("1. Get bread")
print("2. Add filling")
print("3. Close sandwich")
print("------")
print("1. Get bread")
print("2. Add filling")
print("3. Close sandwich")

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1.3. Creating Our First Function

Solution with functions:

def make_sandwich():
    print("1. Get bread")
    print("2. Add filling")
    print("3. Close sandwich")
    print("------")

make_sandwich()
make_sandwich()
make_sandwich()

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1.4. Making Functions Flexible

Adding parameters:

def make_sandwich(filling):
    print("Making " + str(filling) + " sandwich:")
    print("1. Get bread")
    print("2. Add " + str(filling))
    print("3. Close sandwich")
    print("------")

make_sandwich("ham")
make_sandwich("cheese")

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1.5. Modules: Like Game Sound Library

Real-life example:

Game sound module = import sound_effects
Ready-to-use sounds = jump_sound(), explosion_sound()

Simple Python example:

# sound_module.py
def play_jingle():
    print("🎵 Happy tune playing! 🎵")

# main.py
import sound_module
sound_module.play_jingle()

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1.6. Building Our Own Module

Create `kitchen.py`:

def microwave_beep():
    print("BEEP! BEEP! BEEP!")

def oven_timer():
    print("DING! Food is ready!")

Use it:

import kitchen
kitchen.microwave_beep()
kitchen.oven_timer()

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1.7. Example: Cooking Module

Complete example:

# In cooking_module.py
def prepare_dish(dish_name):
    print("Preparing " + str(dish_name) + "...")
    print("1. Gather ingredients")
    print("2. Follow recipe steps")

# In main program
import cooking_module
cooking_module.prepare_dish("pasta")
cooking_module.prepare_dish("salad")

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1.8. Example: Game Sounds

# sound_effects.py
def laser_blast():
    print("PEW! PEW! ")

def power_up():
    print(" ENERGY RESTORED!")

# game.py
import sound_effects
sound_effects.laser_blast()
sound_effects.power_up()

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1.9. Key Takeaways

Functions are like preset shortcuts
Parameters make functions flexible
Modules help organize code
Import lets reuse code
Combine functions/modules for complex programs

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Section 2. Function Basic Syntax

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2.1. What is a Function?

Like a recipe:

Receive ingredients (parameters)
Follow steps (code block)
Give result (return value)

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2.2. Function Structure

def magic_oven(ingredient):  # Function header
    output = str(ingredient) + " cookie" # Function body
    return(output)

Three essential parts:

def statement with function name
Action-performing code block
return the result (optional)

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2.3. Demo 1: Greeting

def greet(name):
    print("Hello, " + str(name))

greet("Alice")  # Output: Hello, Alice!
greet("Bob")    # Output: Hello, Bob!

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2.4. Shape-Shifting Greetings (Multiple Parameters)

def flexible_greet(name, greeting):
    print(str(greeting) + ' ' + str(name) + '!')

flexible_greet("Charlie", "Good morning")
flexible_greet("Diana", "Ni hao")
flexible_greet("Eric", "Guten Tag")

Parameters order matters!

(greeting, name) vs (name, greeting)

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2.5. Calculator Function (Return Value)

def circle_area(radius):
    area = 3.14 * radius ** 2
    return(area)

print(circle_area(5))
print("Pizza area: " + str(circle_area(30)))

pizza_price = circle_area(30) * 0.02

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2.6. Common Mistakes

Case 1: Missing Colon

# Wrong
def bad_function()
    print("Oops")

# Right
def good_function():
    print("Yay!")

Case 2: Wrong Indentation

# Wrong
def messy_function():
print("No indent!")

# Right
def clean_function():
    print("Perfect!")

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2.7. Parameter-Free Functions

import datetime

def show_time():
    now = datetime.datetime.now()
    print("Current time: " + str(now.hour) + ':' + str(now.minute))

show_time()

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2.8. Multi-Parameter Function (BMI)

def calculate_bmi(weight, height):
    """Calculate Body Mass Index"""
    bmi = weight / (height ** 2)
    return(bmi)

print("BMI:", calculate_bmi(70, 1.75))
print("BMI:", calculate_bmi(65, 1.68))

Health tip:

Normal BMI range: 18.5 - 24.9

Question: BMI and weight => height

Question: “x^1/2” vs. “x^(1/2)”

Question: How can we check the correctness of “BMI and weight => height”?

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2.9. Function Superpowers

Reusable code blocks
Clear program structure
Easy error tracking
Team collaboration

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Section 3. Advanced Parameters & Return Values

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3.1. Positional vs Keyword Arguments

Pizza Ordering System Example

def make_pizza(size, toppings):
    print("Making " + str(size) + "cm pizza with:")
    for topping in toppings:
        print(topping)

# Positional arguments
make_pizza(30, ["mushrooms", "olives"])

# Keyword arguments
make_pizza(toppings=["cheese"], size=20)

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3.2. When to Use Keyword Arguments?

When passing many parameters
When parameters have default values
To improve code readability

Try this bad example:

# Confusing positional arguments
make_pizza(["pepperoni"], 25)

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3.3. Default Parameters

Shipping Cost Calculator

def calculate_shipping(weight, base_fee=5.0):
    price = weight * 1.2 + base_fee
    return(price)

print(calculate_shipping(3.5))       # Uses default base_fee
print(calculate_shipping(2.0, 4.0))

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3.4. Multiple Return Values

Box Dimension Calculator

def box_calculator(length, width, height):
    volume = length * width * height
    surface = 2 * (length*width + length*height + width*height)
    return(volume, surface)  # Returns a tuple!

dimensions = box_calculator(5, 3, 2)
print("Volume: " + str(dimensions[0]) + ", Surface: " + str(dimensions[1]))

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3.5. Unpacking Return Values

# Direct unpacking
vol, surf = box_calculator(2, 2, 2)
print("Perfect cube: " + str(vol) + " cubic units")

# Works with different variable names
v, s = box_calculator(1, 3, 5)

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3.6. Variable Scope Experiment

temperature = 25  # Global variable

def adjust_temp():
    temperature = 18  # Local variable
    print("Inside: " + str(temperature) + "°C")

adjust_temp()
print("Outside: " + str(temperature) + "°C")  # Still 25

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3.7. Global Keyword Demo

score = 0

def update_points():
    global score
    score = score + 10
    print("New score: " + str(score))

update_points()  # Now modifies the global variable

print(score)

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3.8. Good Function Names

# Good examples
def calculate_tax(income):
def get_user_profile(id):
def convert_to_fahrenheit(celsius):

# Bad examples
def tax(inc):          # Too vague
def user(id):          # Verb missing
def temp_conv(c):      # Unclear abbreviation

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3.9. Function Name Checklist

Use underscore separation
Be specific but concise
Keep under 3 words when possible

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3.10. Summary

Key concepts covered:

Argument types (positional/keyword)
Default parameter values
Returning multiple values
Variable scope
Naming best practices

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Section 4. Python Modules System

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4.1. Today’s Learning Goals

Understanding different import methods
Working with Python standard libraries
Creating and using custom modules
Namespace concept

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4.2. Basic Module Import Methods

Full Module Import

import math

print(math.sqrt(25))  # 5.0
print(math.pi)        # 3.141592653589793

![Down Arrow] Key points:

Access elements with dot notation
Avoids naming conflicts

Specific Function Import

from random import randint

lottery = [randint(1, 50) for _ in range(6)]
print("Winning numbers: " + str(lottery))

Example output:

Winning numbers: [14, 37, 5, 23, 42, 19]

![Warning] Be careful with name collisions!

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4.3. Math Library in Action

import math

a = 3
b = 4
c = math.sqrt(a**2 + b**2)
print("The hypotenuse is: " + str(c))

Output:

The hypotenuse is: 5.0

Question: change f-string (f”The hypotenuse is: {c}”) into “+” format.

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4.4. Random Library Fun

from random import choice

participants = ["Alice", "Bob", "Charlie", "Diana"]
winner = choice(participants)
print("Congratulations " + winner + "!")

Possible output:

Congratulations Charlie!

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4.5. Time Library Demo

import time

print("Starting countdown:")
for i in range(5, 0, -1):
    print(i)
    time.sleep(1)

print("Blast off! ")

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4.6. Creating Your First Module

Create mymodule.py:

def greet(name):
    return "Hello " + name + ", from my module!"

In main program:

import mymodule

print(mymodule.greet("Sarah"))

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4.7. Understanding Namespaces

import math
import mymath  # Hypothetical custom math module

print(math.sqrt(16))  # 4.0
print(mymath.sqrt(16)) # Maybe different implementation

![Toolbox Analogy] Each module is like a separate toolbox

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4.8. Exploring Third-Party Libraries

# requests example
import requests

response = requests.get("https://www.bioinfo-lab.com/")
print("Status code: " + str(response.status_code))
print("Response time: " + str(response.elapsed.total_seconds()) + "s")

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4.9. Module Search Path

import sys

print("Python looks in these locations:")
for path in sys.path:
    print("- " + str(path))

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4.10. Import Best Practices

Keep imports at top of file
Use aliases for long names:

import numpy as np
import pandas as pd

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Section 5. Practical Python Examples for Beginners

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5.1. Roadmap

Auto-generated Password Program
Simple Calculator
Temperature Conversion System

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5.2. Example 1: Password Generator (1/2)

Problem: Create random secure passwords

import random

def generate_password(length=8):
    chars = "abcdefghijkmnpqrstuvwxyz23456789"
    this_password = ''
    i = 1
    while(i <= length):
        this_password = this_password + random.choice(chars)
        i = i + 1
    return(this_password)

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5.3. Example 1: Password Generator (2/2)

Usage:

print(generate_password())   # Example: 'a3x7bk9m'
print(generate_password(12)) # Example: 'wxn58k2q9yr7'

Question: how can we add random uppercase and lowercase characters?

Hint: random.random(), lower(), upper()

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5.4. Example 2: Simple Calculator (1/2)

Core logic:

def calculator(a, b, operator="+"):
    if operator == "+":
        return a + b
    elif operator == "-":
        return a - b

Question: how can we add “*” and “/”?

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5.5. Example 2: Simple Calculator (2/2)

Using our calculator:

print(calculator(5, 3))           # 8 (uses default +)
print(calculator(5, 3, "-"))      # 2
print(calculator(2.5, 4, "+"))    # 6.5

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5.6. Example 3: Temperature Converter (1/2)

Conversion formulas:

Celsius to Fahrenheit: (C × 9/5) + 32

def c_to_f(c):
    return (c * 9/5) + 32

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5.7. Example 3: Temperature Converter (2/2)

Test conversions:

print(c_to_f(0))
print(c_to_f(100))

Question: write the function “f_to_c”

Question: How can we check the correctness of “f_to_c”

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End

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Content:

Section 1. Introduction to Function & Module

1.1. Functions: Like a Microwave Preset Button

Real-life analogy:

Python example:

1.2. Why do We Need Functions

Problem without functions:

1.3. Creating Our First Function

Solution with functions:

1.4. Making Functions Flexible

Adding parameters:

1.5. Modules: Like Game Sound Library

Real-life example:

Simple Python example:

1.6. Building Our Own Module

Create kitchen.py:

Use it:

1.7. Example: Cooking Module

Complete example:

1.8. Example: Game Sounds

1.9. Key Takeaways

Section 2. Function Basic Syntax

2.1. What is a Function?

2.2. Function Structure

Three essential parts:

2.3. Demo 1: Greeting

2.4. Shape-Shifting Greetings (Multiple Parameters)

Parameters order matters!

2.5. Calculator Function (Return Value)

2.6. Common Mistakes

Case 1: Missing Colon

Case 2: Wrong Indentation

2.7. Parameter-Free Functions

2.8. Multi-Parameter Function (BMI)

Health tip:

Question: BMI and weight => height

Question: “x^1/2” vs. “x^(1/2)”

Question: How can we check the correctness of “BMI and weight => height”?

2.9. Function Superpowers

Section 3. Advanced Parameters & Return Values

3.1. Positional vs Keyword Arguments

Pizza Ordering System Example

3.2. When to Use Keyword Arguments?

Try this bad example:

3.3. Default Parameters

Shipping Cost Calculator

3.4. Multiple Return Values

Box Dimension Calculator

3.5. Unpacking Return Values

3.6. Variable Scope Experiment

3.7. Global Keyword Demo

3.8. Good Function Names

3.9. Function Name Checklist

3.10. Summary

Section 4. Python Modules System

4.1. Today’s Learning Goals

4.2. Basic Module Import Methods

Full Module Import

Specific Function Import

4.3. Math Library in Action

Question: change f-string (f”The hypotenuse is: {c}”) into “+” format.

4.4. Random Library Fun

4.5. Time Library Demo

4.6. Creating Your First Module

4.7. Understanding Namespaces

4.8. Exploring Third-Party Libraries

4.9. Module Search Path

4.10. Import Best Practices

Section 5. Practical Python Examples for Beginners

5.1. Roadmap

5.2. Example 1: Password Generator (1/2)

5.3. Example 1: Password Generator (2/2)

Question: how can we add random uppercase and lowercase characters?

Hint: random.random(), lower(), upper()

5.4. Example 2: Simple Calculator (1/2)

Question: how can we add “*” and “/”?

5.5. Example 2: Simple Calculator (2/2)

5.6. Example 3: Temperature Converter (1/2)

Create `kitchen.py`: