Set creation in Python

Introduction

Sets help you store unique items without any order. They are useful when you want to avoid duplicates.

You want to keep a list of unique friends' names.

You need to remove repeated numbers from a list.

You want to check if an item is in a group quickly.

You want to combine two groups but keep only unique items.

Syntax

Python

my_set = {item1, item2, item3}
# or
my_set = set([item1, item2, item3])

Use curly braces {} to create a set with items inside.

Use set() function to create a set from other collections like lists.

Examples

Create a set of fruits using curly braces.

Python

fruits = {'apple', 'banana', 'cherry'}

Create a set from a list of numbers using the set() function.

Python

numbers = set([1, 2, 3, 4])

Create an empty set using set(), because {} creates an empty dictionary.

Python

empty_set = set()

Sample Program

This program creates a set with some fruits, including a duplicate 'apple'. It prints the set showing only unique items. Then it creates and prints an empty set.

Python

fruits = {'apple', 'banana', 'apple', 'cherry'}
print(fruits)

empty_set = set()
print(empty_set)

Important Notes

Sets do not keep the order of items, so the printed order may vary.

Duplicates are automatically removed when creating a set.

Use set() to create an empty set, because {} creates an empty dictionary.

Summary

Sets store unique items without order.

Create sets using curly braces or the set() function.

Empty sets must be created with set(), not {}.