Python 101: Sets

Python Sets

• https://www.w3schools.com/python/python_sets.asp

• In Python, a set is a collection of unique elements, and it is an unordered and unindexed collection of items.

• Set is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Tuple, and Dictionary, all with different qualities and usage.

*A set is a collection which is unordered, unchangeable, and unindexed.**

• Unordered means that the items in a set do not have a defined order. Set items can appear in a different order every time you use them, and cannot be referred to by index or key.
• Set items are unchangeable, meaning that we cannot change the items after the set has been created. Once a set is created, you cannot change its items, but you can remove items and add new items.
• The values True and 1 are considered the same value in sets, and are treated as duplicates. The values False and 0 are considered the same value in sets, and are treated as duplicates.

Definition and Creation

Definition:

• A set is defined by placing all the elements inside curly braces {}, separated by commas.
• Sets can store all forms of data, such as strings, integers, floats, and even a combination of different data types.
• It’s important to note that sets do not allow duplicate elements.

Example:

# Creating a set
my_set = {1, 2, 3, 4, 5}
print(my_set)  # Output: {1, 2, 3, 4, 5}

Operations and Methods

Operations:

• Sets can be used to perform various set operations such as union, intersection, difference, and more.
• These operations are useful for comparing and manipulating sets.

Example:

# Set operations
set1 = {1, 2, 3}
set2 = {3, 4, 5}
print(set1.union(set2))  # Output: {1, 2, 3, 4, 5}
print(set1.intersection(set2))  # Output: {3}
print(set1.difference(set2))  # Output: {1, 2}

Methods:

• Python provides built-in methods for sets, such as add(), remove(), clear(), and more, to manipulate and perform operations on sets.

Example:

# Set methods
my_set.add(6)  # Adds an element to the set
my_set.remove(3)  # Removes a specific element from the set
print(my_set)  # Output: {1, 2, 4, 5, 6}

Advantages and Comparison

Advantages:

• Sets internally make use of a data structure called a hash table, which provides highly optimized methods for checking whether a specific element is contained in the set or not.
• Sets are unordered and do not allow duplicate elements, making them efficient for certain operations.

Comparison:

• Compared to other data structures like lists and tuples, sets have the advantage of faster element lookup due to their internal implementation using hash tables.

Example:

# Set advantage and comparison
# Faster element lookup in sets compared to lists
my_list = [1, 2, 3, 4, 5]
my_set = {1, 2, 3, 4, 5}
print(3 in my_list)  # Output: True
print(3 in my_set)  # Output: True

# Creating sets
set_a = {1, 2, 3, 4}
set_b = {3, 4, 5, 6}

# Adding an element
set_a.add(5)

# Removing an element
set_b.remove(6)

# Union of two sets
union_set = set_a | set_b  # or set_a.union(set_b)

# Intersection of two sets
intersection_set = set_a & set_b  # or set_a.intersection(set_b)

# Difference of two sets
difference_set = set_a - set_b  # or set_a.difference(set_b)

print("Set A:", set_a)
print("Set B:", set_b)
print("Union:", union_set)
print("Intersection:", intersection_set)
print("Difference:", difference_set)

Methods