How many times can an array be flatten?

Question

For example: if I have a 2d array

arr = [[1,2], [4,5], [7,5], 8]

the output should be 1, since it can be flatten once. If I have a 1d array

arr = [1,3,4]

the output should be 0 since it can't be flatten.

What function should I use?

One you write yourself... What if the list has different nesting levels, e.g. `[1,[2,[3,4],5],6]`. — Willem Van Onsem, Oct 09 '17 at 15:29
@WillemVanOnsem if that's the case, follow the highest nesting level — Jimmy Liao, Oct 09 '17 at 15:33
There's no built-in function to do this. You'll need to write one. Try it, and if you get stuck show your attempt and we can help then. — John Kugelman, Oct 09 '17 at 15:35
Why does it matter? You can have a recursive "flattener" that flattens any nested level in one go. — VPfB, Oct 09 '17 at 15:35

score 1 · Accepted Answer · answered Oct 09 '17 at 15:36

1

Using recursion:

def depth(arr):
    if isinstance(arr, list):
        return 1 + max(depth(elem) for elem in arr)
    else:
        return 0

answered Oct 09 '17 at 15:36

Paco H.

The depth of a simple list should be `0`, and furthermore please do not make someones homework. – Willem Van Onsem Oct 09 '17 at 15:37
7

Might be a good idea to cite your [source](https://stackoverflow.com/a/6039153/7954504) @PacoH – Brad Solomon Oct 09 '17 at 15:38
I actually wrote it myself, but I can see how you could come to that conclusion. – Paco H. Oct 09 '17 at 15:39

1 Answers1