Ranges/algorithms for aggregation

[bearophile]

Luís Marques:

> So let's just say that the client is unclear on his 
> requirements, which does happen in the real world anyway :-).

Yes, it happens, But it's a problem, because often if you know 
what you need you can produce the results more efficiently :-)


> (did anyone actually implement it?)

Not yet.


> I'm not sure how if "a dynamic arrays of dynamic arrays of 
> 2-tuples" sufficed that would help with the intermediate step, 
> if we wanted to avoid the sorting step. Did you have anything 
> in particular in mind there?

I think this problem needs a sorting or a hash. One possible 
solution, if you don't need an associative array as output, is to 
use a multiSort followed by a building of groups using slicing. 
It could be efficient enough. Later you search the keys with a 
some kind of binary search.

Bye,
bearophile