Table of Contents

• Lists
  • List Definition
  • Indexing & Slicing
  • List Methods
• Tuples
  • Tuple Definition
  • Accessing Elements
  • Immutability
• Dictionaries
  • Dictionary Definition
  • Accessing & Modifying
  • Dictionary Methods
• Sets
  • Set Definition
  • Set Operations
  • Set Modification

Lists

A list is a mutable, ordered collection that allows duplicate elements.

List Definition

# Creating lists
fruits = ["apple", "banana", "cherry"]
numbers = [1, 2, 3, 4, 5]
mixed = [1, "apple", 3.14, True]

print(fruits)

# Output:
['apple', 'banana', 'cherry']

Indexing & Slicing

fruits = ["apple", "banana", "cherry", "date"]

# Access elements by index
print(fruits[0])  # First element
print(fruits[-1]) # Last element

# Slice the list
print(fruits[1:3]) # Elements at index 1 to 2
print(fruits[:2])  # First two elements
print(fruits[2:])  # All elements from index 2

# Output:
apple
date
['banana', 'cherry']
['apple', 'banana']
['cherry', 'date']

List Methods

# append() - Adds an element to the end of the list
fruits = ["apple", "banana", "cherry"]
fruits.append("date")

# clear() - Removes all elements from the list
fruits.clear()

# copy() - Returns a shallow copy of the list
fruits = ["apple", "banana", "cherry"]
new_list = fruits.copy()

# count() - Counts occurrences of an element
fruits = ["apple", "banana", "apple", "cherry"]
count = fruits.count("apple")

# extend() - Extends the list by appending elements from another iterable
fruits = ["apple", "banana"]
fruits.extend(["cherry", "date"])

# index() - Returns the index of the first occurrence of an element
index = fruits.index("banana")

# insert() - Inserts an element at a specified index
fruits.insert(1, "blueberry")

# pop() - Removes and returns the element at the specified index (default is the last)
popped = fruits.pop()

# remove() - Removes the first occurrence of an element
fruits.remove("banana")

# reverse() - Reverses the elements of the list
fruits.reverse()

# sort() - Sorts the list in ascending order
fruits.sort()

# sort(reverse=True) - Sorts the list in descending order
fruits.sort(reverse=True)

# Output for append():
['apple', 'banana', 'cherry', 'date']

# Output for clear():
[]

# Output for copy():
['apple', 'banana', 'cherry']

# Output for count():
2

# Output for extend():
['apple', 'banana', 'cherry', 'date']

# Output for index():
1

# Output for insert():
['apple', 'blueberry', 'banana', 'cherry', 'date']

# Output for pop():
'cherry'
['apple', 'blueberry', 'banana', 'date']

# Output for remove():
['apple', 'blueberry', 'cherry', 'date']

# Output for reverse():
['date', 'cherry', 'blueberry', 'apple']

# Output for sort():
['apple', 'blueberry', 'cherry', 'date']

# Output for sort(reverse=True):
['date', 'cherry', 'blueberry', 'apple']

Tuples

A tuple is an immutable, ordered collection that allows duplicate elements.

Tuple Definition

# Creating tuples
fruits = ("apple", "banana", "cherry")
numbers = (1, 2, 3, 4)

print(fruits)

# Output:
('apple', 'banana', 'cherry')

Accessing Elements

# Indexing and slicing work similarly to lists
print(fruits[0])  # First element
print(fruits[-1]) # Last element
print(fruits[1:3])# Slicing

# Output:
apple
cherry
('banana', 'cherry')

Immutability

Tuples cannot be modified after creation.

fruits[0] = "orange"  # Attempts to replace the first item of the tuple with "orange", Raises a TypeError

Dictionaries

A dictionary is an unordered collection of key-value pairs, where keys are unique.

Dictionary Definition

person = {
    "name": "Alice",
    "age": 30,
    "city": "New York"
}

print(person)

# Output:
{'name': 'Alice', 'age': 30, 'city': 'New York'}

Accessing & Modifying

# Accessing values by key
print(person["name"])      # Access value
print(person.get("age"))   # Safe access (returns None if key doesn't exist)

# Modifying values
person["age"] = 31         # Update value
person["job"] = "Engineer" # Add new key-value pair

# Output:
Alice
30

Dictionary Methods

# clear() - Removes all elements from the dictionary
person = {"name": "Alice", "age": 30, "city": "New York"}
person.clear()

# copy() - Returns a shallow copy of the dictionary
person = {"name": "Alice", "age": 30, "city": "New York"}
new_person = person.copy()

# fromkeys() - Creates a new dictionary with specified keys and a single value
keys = ["name", "age", "city"]
default_dict = dict.fromkeys(keys, "Unknown")

# get() - Returns the value for a specified key, or a default if the key is not found
value = person.get("name")
missing_value = person.get("job", "Not Found")

# items() - Returns a view object of key-value pairs
items = person.items()

# keys() - Returns a view object of all keys
keys = person.keys()

# pop() - Removes a key and returns its value
age = person.pop("age")

# popitem() - Removes and returns the last inserted key-value pair
last_item = person.popitem()

# setdefault() - Returns the value of a key, or sets it to a default if it doesn't exist
job = person.setdefault("job", "Engineer")

# update() - Updates the dictionary with key-value pairs from another dictionary or iterable
person.update({"age": 31, "city": "San Francisco"})

# values() - Returns a view object of all values
values = person.values()

# Output for clear():
{}

# Output for copy():
{'name': 'Alice', 'age': 30, 'city': 'New York'}

# Output for fromkeys():
{'name': 'Unknown', 'age': 'Unknown', 'city': 'Unknown'}

# Output for get():
Alice
Not Found

# Output for items():
dict_items([('name', 'Alice'), ('age', 30), ('city', 'New York')])

# Output for keys():
dict_keys(['name', 'age', 'city'])

# Output for pop():
30
{'name': 'Alice', 'city': 'New York'}

# Output for popitem():
('city', 'New York')
{'name': 'Alice'}

# Output for setdefault():
Engineer
{'name': 'Alice', 'job': 'Engineer'}

# Output for update():
{'name': 'Alice', 'job': 'Engineer', 'age': 31, 'city': 'San Francisco'}

# Output for values():
dict_values(['Alice', 'Engineer', 31, 'San Francisco'])

Sets

A set is an unordered collection of unique elements.

Set Definition

# Creating sets
fruits = {"apple", "banana", "cherry"}
numbers = set([1, 2, 3, 4, 4])  # Removes duplicates

print(fruits)
print(numbers)

# Output:
{'banana', 'cherry', 'apple'}
{1, 2, 3, 4}

Set Operations

set1 = {1, 2, 3}
set2 = {3, 4, 5}

# Union
print(set1 | set2)         # Combine elements

# Intersection
print(set1 & set2)         # Common elements

# Difference
print(set1 - set2)         # Elements in set1 but not in set2

# Symmetric Difference
print(set1 ^ set2)         # Elements in either set, but not both

# Output:
{1, 2, 3, 4, 5}
{3}
{1, 2}
{1, 2, 4, 5}

Set Modification

fruits = {"apple", "banana"}

fruits.add("cherry")      # Add element
fruits.update(["date", "fig"]) # Add multiple elements
fruits.remove("banana")   # Remove element (raises KeyError if not found)
fruits.discard("pear")    # Remove element (no error if not found)
fruits.clear()            # Remove all elements

# Output:
{'apple', 'cherry', 'date', 'fig'}
{}