Python | Merge two lists into list of tuples

Given two lists, write a Python program to merge the two lists into list of tuples.

Examples:

Input : list1 = [1, 2, 3]
        list2 = ['a', 'b', 'c']
Output : [(1, 'a'), (2, 'b'), (3, 'c')]

Input : list1 = [1, 2, 3, 4]
        list2 = [ 1, 4, 9]
Output : [(1, 1), (2, 4), (3, 9), (4, '')]

Approach #1 : Naive
Merge both the list into a list of tuple using a for loop. But the drawback is given two lists need to be of the same length.

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def merge(list1, list2):
      
    merged_list = [(list1[i], list2[i]) for i in range(0, len(list1))]
    return merged_list
      
# Driver code
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
print(merge(list1, list2))

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Output:

[(1, 'a'), (2, 'b'), (3, 'c')]

 
Approach #2 : Naive but more efficient
This method remove the above given drawback and work well with uneven lengths of the two lists. It also provide try catch error for Index error.

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def merge(list1, list2):
      
    merged_list = []
    for i in range(max((len(list1), len(list2)))):
  
        while True:
            try:
                tup = (list1[i], list2[i])
            except IndexError:
                if len(list1) > len(list2):
                    list2.append('')
                    tup = (list1[i], list2[i])
                elif len(list1) < len(list2):
                    list1.append('')
                    tup = (list1[i], list2[i])
                continue
  
            merged_list.append(tup)
            break
    return merged_list
  
# Driver code
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
print(merge(list1, list2))

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Output:

[(1, 'a'), (2, 'b'), (3, 'c')]

 
Approach #3 : Using zip()
using zip() method to merge the two list elements and then typecasting into tuple.

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def merge(list1, list2):
      
    merged_list = tuple(zip(list1, list2)) 
    return merged_list
      
# Driver code
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
print(merge(list1, list2))

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Output:

((1, 'a'), (2, 'b'), (3, 'c'))

 
Approach #4 : Using enumerate(), alternative to zip().

This method uses two for loops to enumerate through lists and merge the two lists.

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def merge(list1, list2):
      
    merged_list = [(p1, p2) for idx1, p1 in enumerate(list1) 
    for idx2, p2 in enumerate(list2) if idx1 == idx2]
    return merged_list
      
# Driver code
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
print(merge(list1, list2))

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Output:

[(1, 'a'), (2, 'b'), (3, 'c')]

 
Approach #5: Using map() and lambda.

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# Using map() and lambda
def listOfTuples(l1, l2):
    return list(map(lambda x, y:(x,y), l1, l2))
  
# Driver Code
list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
  
print(listOfTuples(list1, list2))

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Output:

[(1, 'a'), (2, 'b'), (3, 'c')]


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