Digital Animation and Story Design Course for Bali Expat Kids

1. Introduction: What Are Variable Collections?

In earlier topics, variables held single values, such as an integer, float, or string. In real-world software and artificial intelligence pipelines, programs frequently need to collect, group, and address multiple related data points together under a single variable name.

Python provides four built-in collection data types to organize multiple elements:

1. Lists
2. Tuples
3. Sets
4. Dictionaries

Data types that allow their contents to be modified after creation are called mutable (changeable), whereas collections that cannot be altered once created are called immutable.

2. Python Lists

Characteristics

• Ordered: Elements maintain a fixed sequence.
• Mutable: You can add, replace, shift, and remove items.
• Allows Duplicates: A list can store multiple identical elements.
• Syntax: Defined using square brackets [ ] with comma-separated values.

Creating a List & Allowing Duplicates

# Creating a list of fruits with a duplicate item ('banana')
fruits = ["apple", "banana", "mango", "banana"]
print(fruits)

Output:

['apple', 'banana', 'mango', 'banana']

Accessing Elements: Positive and Negative Indexing

• Positive Indexing: Starts at 0.
• Negative Indexing: Index -1 is the last element.

fruits = ["apple", "banana", "mango", "banana"]
print(fruits[0])
print(fruits[-1])

Core List Methods

• .append(element) — add to the end
• .insert(index, element) — insert at position
• .remove(element) — remove first match
• .pop() — remove and return last element

Iterating with a for Loop

for item in fruits:
    print(item)

3. Python Tuples

• Ordered and immutable
• Syntax: parentheses ( )

colors = ("red", "green", "blue")
print(colors[1])

Assigning to a tuple index raises TypeError: 'tuple' object does not support item assignment.

numbers = (1, 2, 3, 2, 4, 2)
print(numbers.count(2))
print(numbers.index(3))

4. Python Sets

• Unordered, unique elements only, high performance
• Syntax: curly braces

numbers_set = {1, 2, 3, 4, 4, 5}
print(numbers_set)
numbers_set.add(6)
numbers_set.remove(2)
A = {1, 2, 3}
B = {3, 4, 5}
print(A | B)
print(A & B)
print(A - B)

5. Python Dictionaries

Key-value pairs for structured data and fast lookups.

student = {
    "name": "Ali",
    "age": 22,
    "course": "Data Science"
}
print(student["name"])
print(student.get("age"))
student["age"] = 23
student["city"] = "Lahore"
student.pop("course")

6. Summary Comparison Table

Collection	Syntax	Ordered?	Mutable?	Duplicates?	Primary Use
List	[a, b, c]	Yes	Yes	Yes	Dynamic sequences
Tuple	(a, b, c)	Yes	No	Yes	Fixed records
Set	{a, b, c}	No	Yes	No	Uniqueness, math ops
Dictionary	{k: v}	Key-based	Yes	Keys unique	Structured records