Write a function that merges two lists, alternating elements from both lists. Python code

Question

For example if a = [1, 4, 9, 16] and b = [9, 7, 4, 9, 11], the function returns a new list, result = [1, 9, 4, 7, 9, 4, 16, 9, 11]

This is the code I have so far.

def merge(a,b):
    mergedList =[]
    for i in range(len(a)):
        mergedList.append(a[i])
        mergedList.append(b[i])

def main():
    a = [1,4,9,16]
    b = [9,7,4,9,11]
    print("List a is", a)
    print("List b is", b)
    result = merge(a,b)
    print("The merged list is", result)
main()

The output I get is

List a is [1,4,9,16]
List b is [9,7,4,9,11]
The merged list is None

Does anyone know why the output for the new merged list is None?

your merge function does not return anything. Try adding return mergedList at the end — joostblack, Apr 14 '21 at 06:13
Does this answer your question? [Pythonic way to combine two lists in an alternating fashion?](https://stackoverflow.com/questions/3678869/pythonic-way-to-combine-two-lists-in-an-alternating-fashion) — Ma0, Apr 14 '21 at 06:15

score 1 · Answer 1 · answered Apr 14 '21 at 06:13

1

You have not returned the merged list. Therefore it's value is None. Change the first function to:

def merge(a,b):
    mergedList =[]
    for i in range(len(a)):
        mergedList.append(a[i])
        mergedList.append(b[i])
    return mergedlist

answered Apr 14 '21 at 06:13

Ismail Hafeez

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Write a function that merges two lists, alternating elements from both lists. Python code

1 Answers1