How to combine a number list and a string list into a new list in python using recursion?

Question

I want to combine a number list and a string list

Example a = [1, 2, 3], b = [a, b, c, d]

combine a and b
and the answer should be [1, a, 2, b, 3, c, d]

or a = [1,2,3], b = [b, d]

combine a and b
and the answer should be [1, b, 2, d, 3]

Here is my code

def combine(a, b):
a = [str(int) for int in a]
b = [str(int) for int in b]
if a and b:
if a[0] > b[0]:
a, b = b, a
return [a[0]] + combine(a[1:], b)
return a + b

a = [1, 2, 3]
b = [‘a’, ‘b’, ‘c’, ‘d’]

combine(a, b)

but my result is this

[‘1’, ‘2’, ‘3’, ‘a’, ‘b’, ‘c’, ‘d’]

Asked By: joule.v

||

Source

Answer 1

from itertools import zip_longest

a = [1, 2, 3]
b = ["a", "b", "c", "d"]

def merge_lists(a, b):
    result = []
    for a_, b_ in zip_longest(a, b):
        if a_ is not None:
            result.append(a_)
        if b_ is not None:
            result.append(b_)
    return result

result = merge_lists(a, b)

With recursion

a = [1, 2, 3]
b = ["a", "b", "c", "d"]
result = []
i = 0

def merge_lists(a, b):
    global i
    if i < len(a):
        result.append(a[i])
    if i < len(b):
        result.append(b[i])
    i+=1
    if i < len(b) or i < len(a):
        merge_lists(a, b)

merge_lists(a, b)

Answered By: Eftal Gezer

How to combine a number list and a string list into a new list in python using recursion?

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