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Ublas : |
Subject: Re: [ublas] Row iterators and std
From: Jesse Manning (manning.jesse_at_[hidden])
Date: 2009-07-08 22:20:32
I think i achieved this behavior by using the size1 or size2 member
functions depending on row or column iteration and used ublas::row or
ublas::column to get a matrix_row or matrix_column
so pseudo code would look something like this
// loop over columns getting each row
for (i = 0; i < m.size1(); ++i)
{
matrix_row row = ublas::row(m, i);
std::accumlate(row.begin(), row.end(), 0.0);
}
probably not the best way, but it worked
On Wed, Jul 8, 2009 at 6:50 PM, Jesse Perla <jesseperla_at_[hidden]> wrote:
> Sorry, forgot to post my intended usage. I wanted to use std::transform
> over the rows. Consider something like this and couldn't do to the
> dereference of the row_iterator gives a double type. Are there any other
> ways to do this pattern in ublas?
>
> struct vector_sum
> {
> template<class VectorType>
> double operator()(const VectorType& vec)
> {
> return std::accumulate(vec.begin(), vec.end(), 0.0);
> }
> };
>
> ublas::matrix<double> A(2.2);
> ublas::vector<double> sums(2);
>
> //Sum over rows.
> std::transform(A.begin1(), A.end1(), sums.begin(), vector_sum());
>
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