Python frozenset() Function | immutable List, Tuple, Dictionary Examples

What is Python frozenset and frozenset() function?

Python frozenset is an immutable object and frozenset() method returns a frozenset object initialized with elements from the given iterable. The frozenset() is an inbuilt function in Python.

More about Frozen set: It’s just an immutable version of a Python set object. While elements of a set can modify elements but frozen set remains the same after creation, you can’t change it.

It takes an iterable object as input and makes them immutable (unchangeable). Means elements of the frozen set remain the same after creation.

Syntax

frozenset(iterable)

Parameter Values

An iterable object, like list, set, tuple, dictionary, etc.

Return value

It returns an equivalent frozenset object.

Python frozenset() Function Examples

Let’s see how frozenset() works in Python with different types of iterable objects.

Using frozenset() Function in tuple

Example of creating a frozen set in python.

# tuple of vowels
vowels = ('a', 'e', 'i', 'o', 'u')

fSet = frozenset(vowels)
print('The frozen set is:', fSet)

forzenset List

mylist = ['apple', 'banana', 'orange']
x = frozenset(mylist)
print(x)

Output:

frozenset({‘orange’, ‘apple’, ‘banana’})

Making keys of a dictionary as frozenset

# creating a dictionary  
Student = {"name": "John", "age": 28, "sex": "Male",
           "college": "IIT Bangalore", "address": "Bangalore"}

# making keys of dictionary as frozenset 
key = frozenset(Student)

# printing keys details 
print('The frozen set is:', key) 

Output:

The frozen set is: frozenset({‘name’, ‘college’, ‘sex’, ‘age’, ‘address’})

Error: if try to change the value of a frozenset item.

mylist = ['apple', 'banana', 'orange']
x = frozenset(mylist)
print(x)
x[3] = 'banana'

Output:

frozenset order Python

frozensets, like sets, have no defined order

Q: What if you try to add or remove the item from the frozen object?

Answer: It will throw and error.

TypeError: 'frozenset' object does not support item assignment

Q: How to convert frozenset to normal sets or lists?

Answer: You can easily create a list and tuple from frozenset object using built-in functions. see below example of frozenset to list and tuple:-

fs = frozenset([1, 2, 3, 4, 5])
list1 = list(fs)
print(list1)

tuple1 = tuple(fs)
print(tuple1)

Output:

[1, 2, 3, 4, 5]
(1, 2, 3, 4, 5)

Iterating frozenset elements

Using for loop to iterate through frozen set elements.

fs = frozenset([1, 2, 3, 4, 5, 4, 3])
for x in fs:
    print(x)

Output:

1
2
3
4
5

Note: frozenset can also perform different operations like union, intersection, etc.

Do comment if you have any questions, doubts, and suggestions on this tutorial.

Note:
IDE: PyCharm 2020.1.1 (Community Edition)
macOS 10.15.4
Python 3.7
All Python Examples are in Python 3, so Maybe its different from python 2 or upgraded versions.