Python | Integrity Sorting in two lists

Difficulty Level : Basic
Last Updated : 11 Feb, 2019

Often during the problem solving we come across to many problems where we need to sort the list. But sometimes we would also want to sort the another list so that the elements of are automatically shifted and remain at same index as the first list even after first list get sorted. Let’s discuss certain ways in which this can be done.

Method #1 : Using sorted() + zip() + itemgetter()
Combining the three functions we can possibly achieve the task. The zip functions binds the two list together, sorted function sorts the list and itemgetter function is used to define the metrics against which we need second list to shift, in this case first list.

# Python3 code to demonstrate 
# integrity sorting in two list 
# using sorted() + zip() + itemgetter()
from operator import itemgetter
  
# initializing lists
test_list1 = [3, 4, 9, 1, 6]
test_list2 = [1, 5, 3, 6, 7]
  
# printing original lists
print ("The original list 1 is : " + str(test_list1))
print ("The original list 2 is : " + str(test_list2))
  
# using sorted() + zip() + itemgetter()
# integrity sorting in two list 
res = [list(x) for x in zip(*sorted(zip(test_list1, test_list2),
                                         key = itemgetter(0)))]
  
# printing result 
print ("The lists after integrity sort : " +  str(res))

Output:

The original list 1 is : [3, 4, 9, 1, 6]
The original list 2 is : [1, 5, 3, 6, 7]
The lists after integrity sort : [[1, 3, 4, 6, 9], [6, 1, 5, 7, 3]]

Method #2 : Using sorted() + zip() + lambda function
This method performs the similar task, each function performing the similar function, the difference is just the instead of itemgetter function, lambda function performs the task of assigning a base to sort the list, i.e the first list in this case.

# Python3 code to demonstrate 
# integrity sorting in two list 
# using sorted() + zip() + lambda function
from operator import itemgetter
  
# initializing lists
test_list1 = [3, 4, 9, 1, 6]
test_list2 = [1, 5, 3, 6, 7]
  
# printing original lists
print ("The original list 1 is : " + str(test_list1))
print ("The original list 2 is : " + str(test_list2))
  
# using sorted() + zip() + lambda function
# integrity sorting in two list 
res = [list(i) for i in zip(*sorted(zip(test_list1, test_list2),
                                  key = lambda dual: dual[0]))]
  
# printing result 
print ("The lists after integrity sort : " +  str(res))

Output:

The original list 1 is : [3, 4, 9, 1, 6]
The original list 2 is : [1, 5, 3, 6, 7]
The lists after integrity sort : [[1, 3, 4, 6, 9], [6, 1, 5, 7, 3]]

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