Python | Ways to flatten a 2D list
Given a 2D list, write a Python program to convert the given list into a flattened list.
Method #1: Using chain.iterable()
# Python code to demonstrate # converting 2d list into 1d list # using chain.from_iterables # import chain from itertools import chain ini_list = [[1, 2, 3], [3, 6, 7], [7, 5, 4]] # printing initial list print ("initial list ", str(ini_list)) # converting 2d list into 1d # using chain.from_iterables flatten_list = list(chain.from_iterable(ini_list)) # printing flatten_list print ("final_result", str(flatten_list)) |
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Output:
initial list [[1, 2, 3], [3, 6, 7], [7, 5, 4]] final_result [1, 2, 3, 3, 6, 7, 7, 5, 4]
Method #2: Using list comprehension
# Python code to demonstrate # converting 2d list into 1d list # using list comprehension # import chain from itertools import chain ini_list = [[1, 2, 3], [3, 6, 7], [7, 5, 4]] # printing initial list print ("initial list ", str(ini_list)) # converting 2d list into 1d # using list comprehension flatten_list = [j for sub in ini_list for j in sub] # printing flatten_list print ("final_result", str(flatten_list)) |
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Output:
initial list [[1, 2, 3], [3, 6, 7], [7, 5, 4]] final_result [1, 2, 3, 3, 6, 7, 7, 5, 4]
Method #3: Using functools.reduce
# Python code to demonstrate # converting 2d list into 1d list # using functools.reduce # import functools from functools import reduce ini_list = [[1, 2, 3], [3, 6, 7], [7, 5, 4]] # printing initial list print ("initial list ", str(ini_list)) # converting 2d list into 1d # using functools.reduce flatten_list = reduce(lambda z, y :z + y, ini_list) # printing flatten_list print ("final_result", str(flatten_list)) |
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Output:
initial list [[1, 2, 3], [3, 6, 7], [7, 5, 4]] final_result [1, 2, 3, 3, 6, 7, 7, 5, 4]
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