How to check what data types are in a list, no matter how deep the the list is

Question

I have a list I would like to check what data types are in it, no matter how many levels deep the list goes. I first thought to do this:

all([isinstance(x, (int, float, str, bytes, list, tuple, set, dict)) for x in l])

But it doesn't seem to work:

>>> l = [1, 2, 3, 4, [bytearray(b'1234')]]
>>> all([isinstance(x, (int, float, str, bytes, list, tuple, set, dict)) for x in l])
True

Is there another method to do this? One that works?

Answer 1

You could use the following flatten function:

def flatten(s):
    for e in s:
        if isinstance(e, (tuple, list)):
            yield from flatten(e)
        else:
            yield e

l = [1, 2, 3, 4, [bytearray(b'1234')]]

result = all(isinstance(x, (int, float, str, bytes, list, tuple, set, dict)) for x in flatten(l))
print(result)

Output

False

The advantage of this approach is that you wont have to check the entire list, all will short-circuit if it finds a False .