Python | Swapping sublists over given range

Last Updated : 26 Feb, 2019

The problem of swapping a single number can be extended to the issue of having the list and perform the swap over an entire range which can be a useful utility over a time. This has its application in any kind of data manipulation in various domains. Let’s discuss certain ways in which this can be performed.

Method #1 : Using list slicing and swapping
The lists can be swapped the same ways a variable can be swapped in python but the difference is that instead of variable, we pass a sliced list to be swapped.

# Python3 code to demonstrate 
# swapping sublist 
# using list swapping and slicing 
  
# initializing list  
test_list = [1, 4, 5, 8, 3, 10, 6, 7, 11, 14, 15, 2] 
  
# printing the original list 
print ("The original list is : " + str(test_list)) 
  
# using list swapping and slicing  
# swapping sublist 
test_list[1 : 3], test_list[6 : 8] = test_list[6 : 8], test_list[1 : 3] 
  
# printing result 
print ("The list after sublist swapping : " + str(test_list)) 

Output:

The original list is : [1, 4, 5, 8, 3, 10, 6, 7, 11, 14, 15, 2]
The list after sublist swapping : [1, 6, 7, 8, 3, 10, 4, 5, 11, 14, 15, 2]

Method #2 : Using slice() + itertools.chain.from_iterable()
The slice function can perform the slice functionality to extract a sublist from a list and from_iterable function helps to perform the swap functionality.

# Python3 code to demonstrate swapping  
# sublist using slice() + itertools.chain.from_iterable() 
import itertools 
  
# initializing list  
test_list = [1, 4, 5, 8, 3, 10, 6, 7, 11, 14, 15, 2] 
  
# printing the original list 
print ("The original list is : " + str(test_list)) 
  
# using slice() + itertools.chain.from_iterable() 
# swapping sublist 
slice_1 = test_list[1 : 3] 
slice_2 = test_list[6 : 8] 
slice_temp = [slice(0, 1), slice(6, 8), slice(3, 6), 
              slice(1, 3), slice(8, len(test_list))] 
  
res = list(itertools.chain.from_iterable([test_list[i] 
                                for i in slice_temp])) 
  
# printing result 
print ("The list after sublist swapping : " + str(res)) 

Output:

The original list is : [1, 4, 5, 8, 3, 10, 6, 7, 11, 14, 15, 2]
The list after sublist swapping : [1, 6, 7, 8, 3, 10, 4, 5, 11, 14, 15, 2]

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