Python for AI 105 Warm-up

Acknowledgement: This post is based mainly on TA Dang Nha’s presentation and slides and partly on TA, STA, and peers’ responses from the course, AIO2025, offered by AI VIETNAM.

Relevance: The audience of this lecture were those who have read Python for AI 104, had some coding experience, and known a bit of AI knowledge. Absolute beginners are encouraged to read the material and repeatedly practice coding without AI assistance to strengthen their coding and code-reading skills. Note that only necessary Python knowledge is introduced here.

In today’s post, we’ll talk about classes and objects.

OOP

Object-Oriented Programming (OOP) “bring” the real world into digital world, abstracting real-life concepts and problems into a digital representation that a computer can process.

OOP has four characteristics with the first two introduced later.

• Encapsulation
• Inheritance
• Polymorphism
• Abstraction.

Before OOP, we had procedural programming utilizing functions and basic data structures discussed previously. Functions must be defined in the order that they are used. This leads to its drawback which is the ability to manage a large interconnecting system like social media platforms with so many users and relationships among them.

OOP addresses this issue by grouping objects (subjects) with similar attributes (properties) and methods (behaviors). We name such a group a class. We’ll discuss these concepts in detail in the following sections.

Take library management as an example. Classes can be books, readers, and librarians; each book, reader, and librarian is an object of its class. Each reader should have attributes like name, ID, and contact method. In addition, we need a process of borrowing and returning books. This process is associated with methods of a class. A librarian can lend books and take returns from readers.

Classes and Objects

class ClassName:
    def constructor(self, attribute_value_1, ..., attribute_value_n):
        self.attribute_name_1 = attribute_value_1
        ...
        self.attribute_name_n = attribute_value_n

    def method_name_1(self, attribute_name_1, ..., attribute_name_m):
        # function body
    ...

    def method_name_k(self, attribute_name_1, ..., attribute_name_p):
        # function body

This theme supports creating diagrams directly in markdown using Mermaid. Mermaid enables users to render flowcharts, sequence diagrams, class diagrams, Gantt charts, and more. Simply embed the diagram syntax within a mermaid code block.

Abstraction: Constructor, Attribute, and Method

ClassName is PascalCase, noun attribute name is noun, snake_case method is verb, snake_case

Inheritance

Why Inheritance?

Child classes inherit

Why do We Need Inheritance?

Methods	Purposes	Returned Value	List Updated	Examples
append()	Add a given value to the end	None		a_list.append(10) a_list >>> [4, 5, 6, 7, 4, 7, 10]
insert()	Add a given value to the position of a given index	None		a_list.insert(2,10) a_list >>> [4, 5, 10, 6, 7, 4, 7]
extend()	Concatenate a given list to the original	None		a_list.extend([10, 8]) a_list >>> [4, 5, 6, 7, 4, 7, 10, 8]
pop()	Delete the last element by default or delete by index	Value		a_list.pop(1) >>> 5 a_list >>> [4, 6, 7, 4, 7]
remove()	Delete the first element of a given value	None		a_list.remove(7) a_list >>> [4, 5, 6, 4, 7]
del	Delete a given list of elements	N/A		del a_list[1:4] a_list >>> [4, 7, 7]
clear()	Delete all elements	None		a_list.clear() a_list >>> []
index()	Return the index of the first occurence of a given value	Index		a_list.index(7) >>> 3 a_list >>> [4, 5, 6, 7, 4, 7]
reverse()	Reverse elements	None		a_list.reverse() a_list >>> [7, 4, 7, 6, 5, 4]
sort()	Arrange elements in an increasing order by default	None		a_list.sort() a_list >>> [4, 4, 5, 6, 7, 7]
count()	Return the number of a given value	Number of times an element appears		a_list.count(7) >>> 2 a_list `  »> [4, 5, 6, 7, 4, 7]`
copy()	Make a copy of the list	New list that has the same value as the original		a_list.copy() >>> [4, 5, 6, 7, 4, 7] a_list >>> [4, 5, 6, 7, 4, 7]

Functions	Purposes	Returned Value	List Updated	Examples
len()	Return the number of elements	Quantity		len(a_list) >>> 6
min()	Return the minimum element	Quantity		min(a_list) >>> 4
max()	Return the maximum element	Quantity		max(a_list) >>> 7
sorted()	Arrange elements in an ascending order by default	New List		sorted_a_list = sorted(a_list) sorted_a_list >>> [4, 4, 5, 6, 7, 7]
sum()	Return the sum of all elements	Quantity		sum(a_list) >>> 33
reversed()	Reverse elements	A reverse iterator object
enumerate()	Return a sequence of tuples of matching index and value	An enumerate object
zip()	Take two lists and return an iterator of tuples of values with matching index	A zip object

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From here on in, the material is

Bonus

FAQ

Here are some good questions asked during class. The answers to these questions came from either some admin, TA, STA, or members of AIO2025.

Check List

• Exercise 1 (date)
• Exercise 2 (date)
  • Put on left sock
  • Put on right sock
• Go to school