Re: [ublas] how to iterate over the elements of a mapped_matrix ?

Subject: Re: [ublas] how to iterate over the elements of a mapped_matrix ?
From: Sunil Thomas (sgthomas27_at_[hidden])
Date: 2011-02-07 20:51:30

Hi Riccardo,

  This follows straight from the ublas docs and examples therein..here's a
snippet that may help:

for(itm1 i1 = A.begin1(); i1 != A.end1(); ++i1) {
   int nnz = 0;
   itm2 i2 = i1.begin();
   irow = (int) i2.index1();
   //Loop over each row's non-zero elements
   for(; i2 != i1.end(); ++i2) {
       (m_cols)[nnz] = (int) i2.index2();
       (m_vals)[nnz] = *i2;
       ++nnz;
   }
   //-Some treatment of zero rows...
   if( nnz == 0 ) {
       (m_cols)[nnz] = irow;
       (m_vals)[nnz] = -1.0;
       ++nnz;
   }
   //-Do other stuff...blah blah
}

--Thomas.

On Mon, Feb 7, 2011 at 10:13 AM, <rrossi_at_[hidden]> wrote:

> Dear list,
>
>               i created a mapped_matrix and now i need to iterate over the
> non_zero elements of SOME rows.
>
> say i need all of the elements of row 123... how should i get them?
>
>
>
> thanks in advance
>
> Riccardo
>
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