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This tutorial demonstrates how to convert a list to a set in Python.

Difference between List and Set

Lists and sets are standard Python data types that store values ​​in sequence.

Python list stores comma separated values ​​between square brackets. It is mutable, which means its items can be modified or changed. The thing about Python list is that the items do not need to be of the same type.

Here is an example of a Python list:

list_1 = [1, 2, 3]
list_2 = ["Milk", "Bread", "Eggs"]
# List with multiple data types
list_3 = ["Chocolate", 15.25, 200]

A Python set is an unordered list of unique elements that may have different data types. The object stores comma-separated values ​​and is enclosed in curly braces {}. It is iterable and mutable, but it only stores immutable objects; this means that the set itself can be modified—we can add or remove elements; however, the elements inside the set must not be changed. We cannot use slicing or indexing to modify or access elements inside a set.

Here is an example of a Python set:

set_1 = {1, 2, 3}
set_2 = {"Milk", "Bread", "Eggs"}
# Sets with multiple data types
set_3 = {17.0, "Hello World", (10, 20, 30)}

Now that we know the difference between Python lists and sets, let’s dive deeper into converting lists to sets.

set()Convert a list to a set using the method in Python

The simplest way to convert a list into a set is to use Python's built-in method, set()the set method. set()The set method will automatically remove lists with duplicate values ​​and will keep the same unique elements as the initial list. set()The set method accepts only one argument as a parameter:

*iterable (optional) – a sequence (string, list, tuple, etc.) or a collection of elements

Here is the syntax:

set(iterable)

set()Method returns:

• An empty set if no arguments were passed.
• A constructed collection

Example 1: Converting a Python list with unique values

# initialize a list
_list = [5, 4, 3, 1, 6, 2]

# convert list to set
converted = set(_list)

print(converted)

Output:

{1, 2, 3, 4, 5, 6}

Example 2: Converting a list with repeated values

# initialize a list
grocery_list = ["milk", "bread", "eggs", "bread", "hotdogs", "eggs"]

# convert list to set
converted = set(grocery_list)

print(converted)

Output:

{'eggs', 'bread', 'milk', 'hotdogs'}

As you can see, convertedthe variable now contains only unique values.

Example 3: Converting a list with mixed data types

# initialize a list with mixed data types
grocery_list = ["milk", "bread", "eggs", ("Ham and Cheese", 2000), 19.43]

# convert the grocery_list to set
grocery_set = set(grocery_list)

# display the converted grocery_list
print(grocery_set)

Output:

{'milk', 'bread', 'eggs', ('Ham and Cheese', 2000), 19.43}

Python collections provide a range of methods that you can choose from based on your use case, beyond just converting a list to a set. There are collection methods for performing mathematical operations: union, intersection, difference, and symmetric difference. We can do this by using some of the defined Python collection operators and methods.