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Python – Swap elements in String list

Last Updated : 08 Mar, 2023
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Sometimes, while working with data records we can have a problem in which we need to perform certain swap operation in which we need to change one element with other over entire string list. This has application in both day-day and data Science domain. Lets discuss certain ways in which this task can be performed. 

Method #1 : Using replace() + list comprehension The combination of above functionalities can be used to perform this task. In this, we iterate through list using list comprehension and task of swapping is performed using replace(). 

Python3




# Python3 code to demonstrate
# Swap elements in String list
# using replace() + list comprehension
 
# Initializing list
test_list = ['Gfg', 'is', 'best', 'for', 'Geeks']
 
# printing original lists
print("The original list is : " + str(test_list))
 
# Swap elements in String list
# using replace() + list comprehension
res = [sub.replace('G', '-').replace('e', 'G').replace('-', 'e') for sub in test_list]
 
# printing result
print ("List after performing character swaps : " + str(res))
 






                        










Output : 


The original list is : ['Gfg', 'is', 'best', 'for', 'Geeks']
List after performing character swaps : ['efg', 'is', 'bGst', 'for', 'eGGks']




Time Complexity: O(n) 
Auxiliary Space: O(n)


 Method #2 : Using join() + replace() + split() The combination of above methods can also be used to perform this task. In this, the task of replace is same, but we use join() and split() with same parameter to perform task of list comprehension. 




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# Python3 code to demonstrate 


# Swap elements in String list


# using replace() + join() + split()


 


# Initializing list


test_list = ['Gfg', 'is', 'best', 'for', 'Geeks']


 


# printing original lists


print("The original list is : " + str(test_list))


 


# Swap elements in String list


# using replace() + join() + split()


res = ", ".join(test_list)


res = res.replace("G", "_").replace("e", "G").replace("_", "e").split(', ')


 


# printing result 


print ("List after performing character swaps : " + str(res))



















                        







                        










Output : 


The original list is : ['Gfg', 'is', 'best', 'for', 'Geeks']
List after performing character swaps : ['efg', 'is', 'bGst', 'for', 'eGGks']




Time Complexity: O(n) 
Auxiliary Space: O(n)


Method #3 : Using regex
This task can also be performed using regex. We use sub() method which is used to perform search and replace operation and replace one character with other using regex.
 




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# Python3 code to demonstrate


# Swap elements in String list


# using regex


 


# Initializing list


import re


 


test_list = ['Gfg', 'is', 'best', 'for', 'Geeks']


 


# printing original lists


print("The original list is : " + str(test_list))


 


# Swap elements in String list


# using regex


res = [re.sub('-', 'e', re.sub('e', 'G', re.sub('G', '-', sub))) for sub in test_list]


 


 


# printing result


print("List after performing character swaps : " + str(res))



















                        







                        










Output


The original list is : ['Gfg', 'is', 'best', 'for', 'Geeks']
List after performing character swaps : ['efg', 'is', 'bGst', 'for', 'eGGks']




Time Complexity: O(n) 
Auxiliary Space: O(n)




                                    


                                                                        

                                        

                                            

                                                

                                                    
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                                                    manjeet_04                                                

                                            

                                            

            
                                        

                                        

                                            
    

        
        
    
                                            

                                                
                                                
                                            

                                            

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