How to change list content after applying a function in Python

Question

I wrote a little program that inserts an element in a list. The program uses a binary search algorithm to find the spot where the new element should be allocated. I'm having trouble to change the original list content. What's wrong in my code?

def Insert(TAB,V):

    for i in range(0, len(TAB)):

        j, count = binarySearch(TAB,V)

        TAB = TAB[:j] + [V] + TAB[j:]

        return "index =",j,"comparisons =", count

You want to either return TAB and have something that looks like TAB = Insert(TAB, V), or do not change the returned value but replace TAB = ... with TAB[:] = ... to change the content of the list in place. — Guimoute
– Guimoute, Commented Dec 1, 2020 at 18:13
I want to replace the original list with the new list that includes the new element. — Brasilian_student
– Brasilian_student, Commented Dec 1, 2020 at 18:14
@inspectorG4dget I can't use bisect module. It's an assignment from uni. — Brasilian_student
– Brasilian_student, Commented Dec 1, 2020 at 18:14

Prune · Accepted Answer · 2020-12-01 18:23:34Z

2

    TAB = TAB[:j] + [V] + TAB[j:]

This builds a new list and assigns it to the local variable TAB. IF you expect to change the list in the calling program, then you have to operate directly on that list, not assign to its local avatar.

TAB.insert(j, V)

should do the job.

answered Dec 1, 2020 at 18:23

Prune

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