Python Itertools.chain.from_iterable() (original) (raw)

Last Updated : 12 Jul, 2025

Python's Itertool is a module that provides various functions that work on iterators to produce complex iterators. This module works as a fast, memory-efficient tool that is used either by themselves or in combination to form iterator algebra.Note: For more information, refer to Python ItertoolsThe functions under itertools can be classified into 3 categories

1. Functions producing Infinite Iterators
2. Functions producing Iterators terminating on the shortest input sequence
3. Functions producing Combinatoric generators

Chain.from_iterable() method

The function chain.from_iterable() comes under the category of terminating iterators. This function takes a single iterable as an argument and all the elements of the input iterable should also be iterable and it returns a flattened iterable containing all the elements of the input iterable.

Syntax : chain.from_iterable(iterable)

Example #1:

Python3 1== `

Importing chain class from itertools

from itertools import chain

Single iterable containing iterable

elements(strings) is passed as input

from_iterable = chain.from_iterable(['geeks', 'for', 'geeks'])

printing the flattened iterable

print(list(from_iterable))

`

Output :

['g', 'e', 'e', 'k', 's', 'f', 'o', 'r', 'g', 'e', 'e', 'k', 's']

Example #2:

Python3 1== `

Importing chain class from itertools

from itertools import chain

Single iterable containing iterable

elements(strings and list) is passed

as input

from_iterable = chain.from_iterable(['geeks', 'for', 'geeks', ['w', 'i', 'n', 's']])

printing the flattened iterable

print(list(from_iterable))

`

Output :

['g', 'e', 'e', 'k', 's', 'f', 'o', 'r', 'g', 'e', 'e', 'k', 's', 'w', 'i', 'n', 's']