Sets in Python

2.1 Set and Its Properties

Sets are a special type of collection in programming that helps store unique elements. Simply put, a set is like a basket where you can only put non-repeating items. If you try to put something that's already there, the basket will just ignore it.

Main characteristics of sets:

Uniqueness:

In a set, each element is unique. If you add an element that already exists in the set, it won't be added again.

Unordered:

Unlike lists, elements in a set have no defined order. This means that you can't access elements by index.

Mutable:

Sets can be modified—adding and removing elements, but the elements themselves must be immutable (like numbers, strings, or tuples).

2.2 Creating a Set in Python

Let's look at all the ways to create sets in Python so you have a full arsenal of methods to work with them.

Using Curly Braces

The most common way to create a set is by using curly braces {}. Just like with tuples and lists, you simply list the elements inside the braces:

fruit_set = {"apple", "banana", "cherry"}
print(fruit_set)  # Output: {"banana", "cherry", "apple"}
        

Elements can be of different types, but each element must be unique.

fruit_set = {"apple", 1, 3.25}
print(fruit_set)  # Output: {1, "apple", 3.25} 
        

Using the set() Function

The set() function can be used to create a set from another iterable object like a list, string, or tuple.

From a List

list_to_set = set([1, 2, 3, 4, 4, 5])
print(list_to_set)  # Output: {1, 2, 3, 4, 5} 
        

From a String

string_to_set = set("hello")
print(string_to_set)  # Output: {"h", "e", "l", "o"} 
        

From a Tuple

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

From Another Set

You can create a set from another set, which is useful for making copies.

original_set = {"apple", "banana", "cherry"}
new_set = set(original_set)
print(new_set)  # Output: {"banana", "cherry", "apple"} 
        

Empty Set

To create an empty set, use the set() function. Note that using curly braces {} will create an empty dictionary (dictionary), not a set.

empty_set = set()
print(empty_set)  # Output: set() 
        

2.3 List of Methods

Sets in Python have a set of methods that allow for efficient management of data collections. Here are some of the most popular methods of the set class:

Below, we'll explore the nuances of all these methods and even a bit more.

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Python SELF EN, level 9, lesson 2

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Creating sets.

Creating sets.

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Python SELF EN, level 9, lesson 2

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Unique List.

Unique List.

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