Re: [ublas] Support for more general ranges

Subject: Re: [ublas] Support for more general ranges
From: gsermaid (linuxfever_at_[hidden])
Date: 2013-05-21 13:05:40

Hi,

I am so glad this has already been implemented, thanks very much!

Giorgos

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Message: 1
Date: Mon, 20 May 2013 17:49:30 +0100 (BST)
From: gsermaid <linuxfever_at_[hidden]>
To: "ublas_at_[hidden]" <ublas_at_[hidden]>
Subject: [ublas] Support for more general ranges
Message-ID:
    <1369068570.74879.YahooMailNeo_at_[hidden]>
Content-Type: text/plain; charset="iso-8859-1"

Hi all,

I would like to ask if there is any way to create a vector proxy based on a general range of indices. For example, if I have
a vector

vector<unsigned> x(4);
x <<= 1,2,3,4;

and a vector of indices?

vector<size_t> k(2);
k <<= 0,3;

I would like to be able to create a vector proxy as follows

vector_proxy<unsigned> mysubvector(x, k);

with the property that

mysubvector[i] = x[k[i]].

I know I can create a simple new class which provides this functionality but ideally I also want to have
all the useful iterator functionality and mathematical operations supported by a typical ublas vector. Is this currently supported? If not, is there an easy way to?
implement it and have all the functionality that ublas offer? Finally, do you think something like this could be included in future versions?

Regards,
Giorgos
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Message: 2
Date: 20 May 2013 18:51:54 +0200
From: "oswin krause" <oswin.krause_at_[hidden]>
To: ublas_at_[hidden]
Subject: Re: [ublas] Support for more general ranges
Message-ID: <519A54AA.9020907_at_[hidden]>
Content-Type: text/plain; charset="iso-8859-1"; Format="flowed"

Hi,

take a look at vector_indirect.

On 20.05.2013 18:49, gsermaid wrote:
> Hi all,
>
> I would like to ask if there is any way to create a vector proxy based 
> on a general range of indices. For example, if I have
> a vector
>
> vector<unsigned> x(4);
> x <<= 1,2,3,4;
>
> and a vector of indices
>
> vector<size_t> k(2);
> k <<= 0,3;
>
> I would like to be able to create a vector proxy as follows
>
> vector_proxy<unsigned> mysubvector(x, k);
>
> with the property that
>
> mysubvector[i] = x[k[i]].
>
> I know I can create a simple new class which provides this 
> functionality but ideally I also want to have
> all the useful iterator functionality and mathematical operations 
> supported by a typical ublas vector. Is this currently supported? If 
> not, is there an easy way to
> implement it and have all the functionality that ublas offer? Finally, 
> do you think something like this could be included in future versions?
>
> Regards,
> Giorgos
>
>
> _______________________________________________
> ublas mailing list
> ublas_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/ublas
> Sent to: Oswin.Krause_at_[hidden]

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