Re: RANK

[Ben Pfaff]

John Darrington <address@hidden> writes:

> I've been looking at possible ways to implement the RANK command.  A problem
> arises in that it's necessary to sort the data (in order to assign ranks), but
> the original case order should remain unchanged.
>
> One way would be to insert all the cases into a hash and use hsh_sort, but 
> this would not scale well.
>
> A better way would be to use sort_active_file_to_casefile (from sort.c) and 
> then to use casereader_read  to iterate the cases.  This seems more 
> attractive,
> however, the problem is that since the cases have been copied, we've lost our
> place in the original casefile.
>
> I wonder if it would be possible to have a specialised class of
> casefile, whose cases contain pointers to their original source
> case?

I think this may be essentially what we need to solve the
problem.  It's on my list of things to do, but I don't know when
I'll get around to it.  If you decide to work on it, can you try
to post a proposed design to the list before implementing?  I'm
trying to keep the casefile design clean, so I'd like an
opportunity to give feedback before any major changes to it are
checked in.
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