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Python | Concatenate two lists element-wise
  • Last Updated : 28 Jan, 2019

Sometimes we come across this type of problem in which we require to leave each element of one list with the other. This type of problems usually occurs in developments in which we have the combined information, like names and surnames in different lists. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using list comprehension + zip()
List comprehension does the task of concatenating the similar index elements. The task of zip function is concatenating the resultant string into a single list and return list.




# Python3 code to demonstrate 
# interlist element concatenation
# using list comprehension + zip()
  
# initializing lists  
test_list1 = ["Geeksfor", "i", "be"]
test_list2 = ['Geeks', 's', 'st']
  
# printing original lists
print ("The original list 1 is : " + str(test_list1))
print ("The original list 2 is : " + str(test_list2))
  
# using list comprehension + zip()
# interlist element concatenation
res = [i + j for i, j in zip(test_list1, test_list2)]
  
# printing result 
print ("The list after element concatenation is : " +  str(res))
Output:
The original list 1 is : ['Geeksfor', 'i', 'be']
The original list 2 is : ['Geeks', 's', 'st']
The list after element concatenation is : ['GeeksforGeeks', 'is', 'best']

 
Method #2 : Using map() + lambda + zip()
The task of mapping each index element with each other is performed by map function in this method and the functionality of addition is performed by lambda function. This method works only in Python2.




# Python code to demonstrate 
# interlist element concatenation
# using map() + lambda + zip()
  
# initializing lists  
test_list1 = ["Geeksfor", "i", "be"]
test_list2 = ['Geeks', 's', 'st']
  
# printing original lists
print ("The original list 1 is : " + str(test_list1))
print ("The original list 2 is : " + str(test_list2))
  
# using map() + lambda + zip()
# interlist element concatenation
res = list(map(lambda(i, j): i + j, zip(test_list1, test_list2)))
  
# printing result 
print ("The list after element concatenation is : " +  str(res))
Output:
The original list 1 is : ['Geeksfor', 'i', 'be']
The original list 2 is : ['Geeks', 's', 'st']
The list after element concatenation is : ['GeeksforGeeks', 'is', 'best']

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