Bypassing boost :: ublas macro using iterators
I just want to traverse the matrix from start to finish, touching each element. However, I see that there is no iterator to raise the matrix, but there are two iterators, and I have not been able to figure out how to get them to work so that you can traverse the whole matrix
typedef boost::numeric::ublas::matrix<float> matrix;
matrix m1(3, 7);
for (auto i = 0; i < m1.size1(); i++)
{
for (auto j = 0; j < m1.size2(); j++)
{
m1(i, j) = i + 1 + 0.1*j;
}
}
for (auto itr1 = m1.begin1(); itr1!= m1.end1(); ++itr1)
{
for (auto itr2 = m1.begin2(); itr2 != m1.end2(); itr2++)
{
//std::cout << *itr2 << " ";
//std::cout << *itr1 << " ";
}
}
This code of mine only prints row1 of the matrix using itr1 and only column 1 of the matrix using itr2. What can be done to access all rows and columns?
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1 answer
To iterate over a matrix, iterator2 must be retrieved from iterator1, for example:
for(auto itr2 = itr1.begin(); itr2 != itr1.end(); itr2++)
Complete code:
#include <stdlib.h>
#include <boost/numeric/ublas/matrix.hpp>
using namespace boost::numeric::ublas;
using namespace std;
int main(int argc, char* argv[]) {
typedef boost::numeric::ublas::matrix<float> matrix;
matrix m1(3, 7);
for (auto i = 0; i < m1.size1(); i++) {
for (auto j = 0; j < m1.size2(); j++) {
m1(i, j) = i + 1 + 0.1*j;
}
}
for(matrix::iterator1 it1 = m1.begin1(); it1 != m1.end1(); ++it1) {
for(matrix::iterator2 it2 = it1.begin(); it2 !=it1.end(); ++it2) {
std::cout << "(" << it2.index1() << "," << it2.index2() << ") = " << *it2 << endl;
}
cout << endl;
}
return EXIT_SUCCESS;
}
Outputs:
(0,0) = 1 (0,1) = 1.1 (0,2) = 1.2 (0,3) = 1.3 ...
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