nested list python code example

Example 1: python how to unnest a nested list

# Basic syntax:
unnested_list = list(chain(*nested_list))
# Where chain comes from the itertools package and is useful for 
#	unnesting any iterables

# Example usage:
from itertools import chain
nested_list = [[1,2], [3,4]]
my_unnested_list = list(chain(*nested_list))
print(my_unnested_list)
--> [1, 2, 3, 4]

Example 2: nested loop in list comprehension

# 2-D List 
matrix = [[1, 2, 3], [4, 5], [6, 7, 8, 9]] 
  
# Nested List Comprehension to flatten a given 2-D matrix 
flatten_matrix = [val for sublist in matrix for val in sublist] 
  
print(flatten_matrix)

Example 3: python nested list

# example of a nested list
my_list = [[1, 2], ["one", "two"]]

# accessing a nested list
my_list[1][0] # outputs "one"

Example 4: python nested list

L = [[1, 2, 3],[4, 5, 6],[7, 8, 9]]   
for list in L:
    for number in list:
        print(number, end=' ')
# Prints 1 2 3 4 5 6 7 8 9