Re: [Boost-users] [multi_array] Useful algorithms (from Re: Multi_array: A "proper" iterator over a N>1 Multi_array?)

From: Greg Link (link_at_[hidden])
Date: 2006-05-17 15:44:23

I'm going to second Antonio's comments.  A globally applicable  
iterator across a multi-array's data elements would provide a /very/  
useful tool, and doesn't seem all that impossible to program,  
requiring all the magic be done behind the scenes in operator+ etc.

  In addition, I'd love to see a Boost statistical package, but am  
unfamiliar with the process of getting support for a new boost  
library, nor what the early stages of development look like.

- Greg Link

On May 17, 2006, at 2:46 PM, Antonio Piccolboni wrote:

> As I said in a former message that I am afraid fell through the
> cracks, sorry if I am repeating myself, I don't think rewriting the
> whole STL algorithm lib for multi_array is a solution. for_each,
> accumulate, sort, where do we stop? I recently needed to apply random
> shuffle, for instance. I think the solution is to define iterators
> that provide a "flat", element by element view of a multi_array. These
> iterators would be regular skip iterators that just a have a fancy
> increment operation that looks at the stride vector to decide by how
> much to jump when incremented. Let's say that these are returned by
> begin_element and end_element. Then you could do on multi array ma
> things like
>
> for_each(ma.begin_element(), ma.end_element(), do_something())
>
> or
>
> accumulate(ma.begin_element(), ma.end_element(), 0)
>
> and so on for all STL algorithms, all the statstical functions that I
> wrote (GPLed, maybe the beginning of a boost stats lib?, mail me if
> interested) and more.
> I've been using data() and data()+num_elements for the same purpose,
> but that breaks for non contiguos storage (that is, not guaranteed to
> work for views)
>
> I don't think rewriting all the algorithms for multi_array is a viable
> strategy, nor is in keeping  with the idea that data structures and
> algorithms should be made as ortogonal as reasonably possible.  Just
> my 2c
>
>
> Antonio