Got an AttributeError when i'm call list.count() function

Question

I'm solving some katas in CodeWars and in the current kata I'm trying to get how many times an element has occurred in a list that I set as a parameter, then and use it as the range of a for loop.

However, when I call the function it returns:

File "<pyshell#8>", line 3, in delete_nth 
if order.count(item) > max_e:
    AttributeError: 'NoneType' object has no attribute 'count'

here is my code

def delete_nth(order,max_e):
    for item in order:
        if order.count(item) > max_e:
            for i in range(order.count(item) - max_e):
                order = order.remove(item)
    return order

l = [20,37,20,21]
delete_nth(l,1) #except [20,37,21]

Are you programming in the correct Python version? – S.S. Anne May 18 '19 at 15:36 — S.S. Anne, May 18 '19 at 15:36
`order = order.remove(item)` -> `order.remove(item)`. – Austin May 18 '19 at 15:37 — Austin, May 18 '19 at 15:37

score 1 · Accepted Answer · answered May 18 '19 at 15:41

1

The problem is this statement order = order.remove(item) You don't have to reassign list after removing an item. And also list.remove returns None which the cause of your error.

So edit it to this: order.remove(item)

answered May 18 '19 at 15:41

Naman Jain

28
6

long time but it helped me at the time. thank you – LiadS Sep 18 '20 at 09:38

score 0 · Answer 2 · answered May 18 '19 at 15:38

The problem is that you are changing order even as you are iterating through it. You should not be doing it. If you want create a copy of the existing list and modify it.

remove function doesn't return anything, so, effectively None gets assigned to order.

def delete_nth(order,max_e):
    for item in order:
        if order.count(item) > max_e:
            for i in range(order.count(item) - max_e):
                order = order.remove(item) ======> order becomes None as remove returns None.
    return order

Got an AttributeError when i'm call list.count() function

2 Answers2