Merge Sort Problems In Python

Question

So I'm trying to teach myself how to write a merge sort but for whatever reason I can't seem to make it work.

    def merge(left, right):
        result = []
        i ,j = 0, 0
        while i < len(left) and j < len(right):
            if left[i] <= right[j]:
                result.append(left[i])
                i += 1
            else:
                result.append(right[j])
                j += 1
        result += left[i:]
        result += right[j:]
        return result

    def mergesort(numlist):
        if len(numlist) < 2:
            return numlist
        middle = int(len(numlist)/2)
        left = mergesort(numlist[:middle])
        right = mergesort(numlist[middle:])
        return merge(left, right)

Every list I feed into the sort then attempt to print just comes up the exact same with no changes

Answer 1

Answering so this can be closed though it was fixed in comments with the help of @Jean-François Fabre.

Your current code works fine but it does not sort the list in-place. In the case of sorting a list called list_of_numbers , you need to assign the result back to list_of_numbers :

list_of_numbers = mergesort(list_of_numbers)