Sets

A set is an unordered collection of unique elements as opposed to [lists](/tutorials/list) in which elements are ordered and need not be unique. Sets are useful when you want to store a collection of items without any duplicates and don't require the elements to be in a specific order.

To create a set, you can use curly braces `{}` or the `set()` function. Here's an example:


fruits = {"apple", "banana", "orange"}
In this code, we create a set called `fruits` that contains three elements: `"apple"`, `"banana"`, and `"orange"`. Note that the order of the elements may vary when printed because sets are unordered.

Sets have several useful properties and methods. Let's explore some of them with practical examples:

### Adding and Removing Elements

You can add elements to a set using the `add()` method and remove elements using the `remove()` method. Here's an example:


fruits = {"apple", "banana", "orange"}
fruits.add("kiwi")
fruits.remove("banana")
print(fruits)  # Output: {"apple", "orange", "kiwi"}
{'kiwi', 'apple', 'orange'}

In this code, we add the element `"kiwi"` to the `fruits` set using the `add()` method. We then remove the element `"banana"` using the `remove()` method. The resulting set contains `"apple"`, `"orange"`, and `"kiwi"`.

### Checking Membership

You can check if an element is present in a set using the `in` keyword. Here's an example:


fruits = {"apple", "banana", "orange"}
print("banana" in fruits)  # Output: True
print("kiwi" in fruits)  # Output: False
True
False

In this code, we check if the elements `"banana"` and `"kiwi"` are present in the `fruits` set. The `in` keyword returns `True` if the element is present and `False` otherwise.

### Set Operations

Sets support various mathematical set operations, such as union, intersection, and difference. Here's an example:


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

union = set1.union(set2)
intersection = set1.intersection(set2)
difference = set1.difference(set2)

print(union)  # Output: {1, 2, 3, 4, 5}
print(intersection)  # Output: {3}
print(difference)  # Output: {1, 2}
{1, 2, 3, 4, 5}
{3}
{1, 2}

In this code, we perform set operations on `set1` and `set2`. The `union()` method returns a set containing all the unique elements from both sets. The `intersection()` method returns a set containing the common elements. The `difference()` method returns a set containing the elements that are in `set1` but not in `set2`.

Sets provide a convenient way to work with collections of unique elements and perform set operations efficiently.

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