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Ublas : |
From: Nizar Khalifa Sallem (nksallem_at_[hidden])
Date: 2008-07-21 12:10:56
James Sutherland wrote:
>>
>> Hi,
>> I am using sparse matrix to store size 2 vectors and I am facing a
>> little problem.
>> I want just to, let's say, dsplay element of the matrix only if they
>> exist, but I couldn't find any method to access non zero element
>> indexes or to make existency check. Am I wrong, does such methods
>> exist ?
>> Here is a sample code:
>> ___________________________
>> void TestProxies::testSparseMatrix2() {
>> using namespace boost::numeric::ublas;
>> compressed_matrix<bounded_vector<double, 2> > m(3,3,2);
>> bounded_vector<double, 2> v1, v2;
>>
>> v1(0) = 1.1;
>> v1(1) = 2.1;
>> v2(0) = 2.13;
>> v2(1) = 3.14;
>> m(0,0) = v1;
>> m(2,1) = v2;
>> std::cout << m << std::endl;
>> for (unsigned i = 0; i < m.size1 (); ++ i) {
>> for (unsigned j = 0; j < m.size2 (); ++ j) {
>> if(m(i,j)) {//it would worked fine if m elements were double and
>> not vectors
>> std::cout << (bounded_vector<double, 2>) m(i,j) << std::endl;
>> }
>> }
>> }
>
>
> use matrix_row:
> matrix_row row(m,rownumber);
> Then you can iterate through the columns.
> for( matrix_row::iterator col=row.begin(); col!=row.end() ){
> // use the col iterator however you want.
> }
>
> James
> _______________________________________________
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Thanks