Re: [Boost-users] Lookup on composite key in MultiIndex

Subject: Re: [Boost-users] Lookup on composite key in MultiIndex
From: Chris Jewell (chris.jewell_at_[hidden])
Date: 2010-12-06 10:30:27

On 3 Dec 2010, at 18:44, JOAQUIN M. LOPEZ MUÑOZ wrote:

> 
> Hi Chris,
> 
> I'm afraid to say that there is no way you can do that with
> Boost.MultiIndex: Any lookup operation with Boost.MultiIndex
> returns a *contiguous* range of elements, and it is mathematically
> impossible to order an arbitrary set of Individual's in a way that
> all the sets of the form
> 
>  Individual::I < T and Individual::N > N
> 
> are contiguous according to the order. These type of bi-dimensional
> lookups require (if you want to make them efficiently) some
> sort of special data structure such as kd-trees. Otherwise the best
> you can do is
> 
>  lookup for Individual::I < T
>  traverse the returned range and filter elements with Individual::N > N
> 
> which is linear in time complexity (but maybe acceptable for your
> needs).

Hi,

Thanks Joaquin, that's very useful to know!

Chris

--
Dr Chris Jewell
Department of Statistics
University of Warwick
Coventry
CV4 7AL
UK
Tel: [phone]