Data Structures in Python

Python provides a variety of built-in data structures, such as lists, tuples, sets, and dictionaries. Each serves unique purposes and can help make code more efficient and organized.

1. Lists

A list is an ordered, mutable data structure in Python that allows duplicate elements. Lists are created using square brackets:

my_list = [1, 2, 3, 4, 5]
print(my_list)

Lists support various methods like append(), remove(), and sort():

my_list.append(6) # Adds 6 to the end
my_list.remove(3)  # Removes the element with value 3
my_list.sort()     # Sorts the list in ascending order

Lists Quiz

How do you add an element to the end of a list?

list.add(item)
list.append(item)
list.insert(item)

What makes lists different from tuples?

Lists are mutable, tuples are immutable
Lists use parentheses, tuples use brackets
Lists can't contain numbers

2. Tuples

A tuple is similar to a list but is immutable, meaning once created, its elements cannot be changed. Tuples are defined using parentheses:

my_tuple = (10, 20, 30)
print(my_tuple)

Because tuples are immutable, they are often used for fixed collections of items.

Tuples Quiz

What happens if you try to modify a tuple element?

Error - tuples are immutable
The element changes successfully
Python automatically converts it to a list

When would you use a tuple instead of a list?

When you need to frequently add/remove items
When you have fixed data that shouldn't change
When you need to sort the elements

3. Sets

A set is an unordered collection of unique elements. Sets are useful for storing distinct items and for membership testing:

my_set = {1, 2, 3, 4, 5}
my_set.add(6)  # Adds 6 to the set
my_set.remove(3)  # Removes the element with value 3

Sets do not allow duplicate elements and are defined using curly braces.

Sets Quiz

What happens if you try to add a duplicate element to a set?

It's ignored (no duplicates allowed)
It replaces the existing element
It causes an error

What's the main advantage of using sets?

They maintain element order
Fast membership testing and unique elements
They can be nested like lists

4. Dictionaries

A dictionary is a collection of key-value pairs. Dictionaries are unordered, mutable, and defined with curly braces:

my_dict = {'name': 'Alice', 'age': 25}
print(my_dict['name'])  # Outputs: Alice

Dictionaries are great for representing structured data, where each key points to a specific value. Methods include get(), keys(), and values().

Dictionaries Quiz

How do you safely access a dictionary value that might not exist?

dict[key]
dict.get(key)
dict.find(key)

What happens if you try to use a list as a dictionary key?

Error - only immutable types can be keys
It works fine
The list gets converted to a string

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