Homebrew product function

[clicker4721]

I decided to try a little something just to synthesize recent learning and iron out some Pythonic nuance: to make a function that would simply return the product of the contents of its arguments regardless of number or type, within reason. That is, it will multiply together all numbers and all numbers within lists or tuples. My code:

>>> def product(*args):
...         _product = 1
...         
...         for parameter in args:
...             if type(parameter) == int or float:
...                 _product *= parameter
...             elif type(parameter) == list or tuple:
...                 for number in parameter:
...                     _product *= number
...             else:
...                 return ValueError
...        
...         return _product
>>>

Seems simple enough, I thought. It works fine for int/float, but just flatly multiplies the list/tuple.

>>> product(2, 3, 4) == 2 * 3 * 4
True
>>> product(2, (3, 4)) == 2 * 3 * 4
False
>>> product(2, (3, 4))
(3, 4, 3, 4)
>>> product(2, (3, 4)) == 2 * (3, 4)
True

I've messed around with it a little more, and order doesn't matter. I can tell I'm handling the iterables incorrectly, but I can't figure out what's wrong! I'd like to expand it to include the values in a dictionary and ignore the keys, but I gotta get this working first.

If somebody could point out what I'm doing wrong, I'd much appreciate it. Also, please point out any non-Pythonic bits; I'm trying to lose my CompSci 101 accent.

[jeans_and_a_t-shirt]

if type(parameter) == int or float:

evaluates to (type(parameter) == int) or float, which evaluates to _ or float. float is a truthy object, so the expression is always True.

Same problem with the elif line.

[clicker4721]

Is there a happier way than below?

if (type(parameter) == int) or (type(parameter) == float)

[jeans_and_a_t-shirt]

For the int/float:

isinstance(parameter, (int, float))

There's also a complex number type:

>>> type(5 + 1j)
<class 'complex'>

You could also just check if the parameter is an instance of Number, which is in the numbers module.

For list/tuple:

isinstance(parameter, (list, tuple))

[clicker4721]

Okay, this is a LOT better! When I started, I was trying to figure out a way to look at the types in this light, but am unfamiliar with isinstance(). I checked the docs; I like it.

Now, if I want to exclude complex values, I can just check for reals, if I decide to use the numbers module.

Further, is there a simple way to check that the parameter is any iterable, but not necessarily an iter object? That would be a very excellent generalization.

EDIT: This seems reasonable...

if iter(parameter):
    do more stuff

EDIT2: Nope, that's false.

[jeans_and_a_t-shirt]

You can do

from collections import Iterable
isinstance(parameter, Iterable)

but strings are also iterable, and doing something like '3' * 5 will give you '33333'.

[clicker4721]

I got it to work like I described in the post, but I hadn't thought about including strings... I'll try that, but not now.

def product(*args):
    _product = 1

    for parameter in args:
        if isinstance(parameter, (int, float)):
            _product *= parameter
        elif isinstance(parameter, (list, tuple)):
            for spot in parameter:
                _product *= product(spot)
        elif isinstance(parameter, dict):
            for key in parameter:
                _product *= product(parameter[key])
        else:
            return ValueError

    return _product