How to flatten a list of iterables in Python
Overview
The from_iterable() method is an alternate constructor for chain in the itertools module that accepts a single iterable as an argument. And all of the input iterable’s elements must also be iterable. It returns a flattened iterable with all of the input iterable’s elements.
Note: The
itertoolsis a module in Python that provides functions. These functions help in iterating through iterables.
Syntax
chain.from_iterable(iterable)
Parameters
iterables: This is iterable which needs to be flattened.
Return value
The method returns a flattened iterable containing all of the input iterable’s elements.
Code example
Let’s look at the code below:
from itertools import chainnum_lst1 = [1, 2, 3]num_lst2 = [2, 3, 4]num_lst3 = [3, 5, 6]print("Flattened list of num_lst1, num_lst2 and num_lst3 - ", list(chain.from_iterable([num_lst1, num_lst2, num_lst3])))str_lst1 = ["educative", "edpresso"]print("Flattened list of str_lst1 - ", list(chain.from_iterable(str_lst1)))str_lst2 = ['h', 'e', 'l', 'l', 'o']str_lst1.append(str_lst2)print("new list - ", str_lst1)print("Flattened list of str_lst1 - ", list(chain.from_iterable(str_lst1)))
Code explanation
- Line 1: We import
chainfrom theitertoolspackage. - Lines 3 to 5: We define three lists,
num_lst1,num_lst2, andnum_lst3. - Line 6: The lists are flattened using the
from_iterable()method. - Line 8: We define a list of strings called
str_lst1. - Line 9: We use the
from_iterable()method to flattenstr_lst1to individual characters in the strings. - Line 11: We define a list of characters called
str_lst2. - Line 12: We append
str_lst2tostr_lst1. - Line 14: We use the
from_iterable()method to flatten `str_lst1.
Output
The output contains the individual characters of the strings and lists in str_lst1.
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