Clean dynamically generated nested Tuples

Question

I have a class whose __iter__() method return a itertools.product() of a dynamically generated data. This data do a Cartesian product of arbitrarily nested dicts, and now I need to flatten it, but in a streamlined way, aggregating intermediate iterators.

I'm trying either of these:

1. Modify __iter__() to handle the internal tuples:

    class Explosion:
        ...
        def __iter__(self):
            return product(*self.fragments)
   

2. Encapsulate it in another object to handle the conversion, but this is less desirable:

    class CleanOutput:
        def __init__(self, it):
            self.it = it
   
        def next(self):
            for x in self.it:
                yield ?
   
    class Explosion:
        ...
        def __iter__(self):
            return CleanOutput(product(*self.fragments))
   

Well, the algorithm does work, but the problem is the unpacking at the final, for example:

(11, ..., (10.7, 104.75, ('N', True, False, 'B2B'), 99.01, ...), 1, 'SP', 7).

Look at all the nesting! How to remove it in real-time? While it is being generated... I'm looking for a way retrieve:

(11, ..., 10.7, 104.75, 'N', True, False, 'B2B', 99.01, ..., 1, 'SP', 7).

What is the best and fastest way to do it? Thank you!

EDIT

Actually, what I'd really like was a list comprehension or a generator expression or even another generator, because I needed to include it in a callable, intercepting the output of the itertools.product() itself. I don't simply need a way to clean these tuples. So it isn't a duplicate.

Answer 1

That wasn't easy, the recursion has to be used, but separated from the main __iter__ method. That's how I ended up doing. Now also with a recursive generator _merge, called by another generator _flatten:

class Explosion:
    # ...

    def __iter__(self):
        def _flatten(container):
            def _merge(t):
                for te in t:
                    if isinstance(te, tuple):
                        for ite in _merge(te):
                            yield ite
                    else:
                        yield te

            for t in container:
                yield tuple(_merge(t))

        return _flatten(product(*self.fragments))

See an example of utilization of the _flatten() function:

>>> list(itertools.product([1,2],[3,(4,(5,6))]))
[(1, 3), (1, (4, (5, 6))), (2, 3), (2, (4, (5, 6)))]
>>> list(_flatten(itertools.product([1,2],[3,(4,(5,6))])))
[(1, 3), (1, 4, 5, 6), (2, 3), (2, 4, 5, 6)]