vector_of_vector

Next Topic
 
classic Classic list List threaded Threaded
2 messages Options
Reply | Threaded
Open this post in threaded view
|

vector_of_vector

Boost - uBLAS mailing list
Hi. I'd like to have a matrix<T> stored in such a way that I can quickly use each row (or else column) as a vector<T>. Seeing the vector_of_vector matrix type, at least the name suggests that this is what I need, but I suspect this is not so because I can't get it to do that. Does anyone have a hint on how to extract an entire row of a matrix into a vector as efficiently as possible? 

Thanks

_______________________________________________
ublas mailing list
[hidden email]
https://lists.boost.org/mailman/listinfo.cgi/ublas
Sent to: [hidden email]
Reply | Threaded
Open this post in threaded view
|

Re: vector_of_vector

Boost - uBLAS mailing list
Maybe use proxies, that are a light-weight view of what is in the matrix?

http://www.boost.org/doc/libs/1_47_0/libs/numeric/ublas/doc/matrix_proxy.htm

example:
#include <boost/numeric/ublas/matrix.hpp>
#include <boost/numeric/ublas/matrix_proxy.hpp>
#include <boost/numeric/ublas/io.hpp>

int main () {
    using namespace boost::numeric::ublas;
    matrix<double> m (3, 3);
    for (unsigned i = 0; i < m.size1 (); ++ i) {
        matrix_row<matrix<double> > mr (m, i);
        for (unsigned j = 0; j < mr.size (); ++ j)
            mr (j) = 3 * i + j;
        std::cout << mr << std::endl;
    }
}

Hi. I'd like to have a matrix<T> stored in such a way that I can quickly use each row (or else column) as a vector<T>. Seeing the vector_of_vector matrix type, at least the name suggests that this is what I need, but I suspect this is not so because I can't get it to do that. Does anyone have a hint on how to extract an entire row of a matrix into a vector as efficiently as possible? 

Thanks


_______________________________________________
ublas mailing list
[hidden email]
https://lists.boost.org/mailman/listinfo.cgi/ublas
Sent to: [hidden email]

_______________________________________________
ublas mailing list
[hidden email]
https://lists.boost.org/mailman/listinfo.cgi/ublas
Sent to: [hidden email]