特征稀疏矩阵获取非零元素的索引 [英] Eigen Sparse Matrix get Indices of Nonzero Elements

问题描述

我第一次使用本征稀疏矩阵，现在我想知道如何获取非零元素的索引. 我构造了稀疏矩阵，如下所示:

I am using Eigen Sparse Matrices for the first time, and now I would like to know how to get the indices of the nonzero elements. I constructed my Sparse Matrix as follows:

Eigen::SparseMatrix<Eigen::ColMajor> Am(3,3);

通过查看m_indices变量，我可以看到VS中的一些索引.但是我无法访问它们.谁能帮帮我吗? 对于像

and I can see some indices in VS by looking into the m_indices variable. But I can't access them. Can anyone please help me? For a Matrix like

( 1 0 1 
  0 1 1
  0 0 0 )

我希望索引像(0,0), (0,2), (1,1), (1,2).

有什么办法吗?

P.S.我的矩阵比3x3大得多.

P.S. My matrices are way bigger than 3x3.

推荐答案

教程的代码与此类似:

for (int k=0; k < A.outerSize(); ++k)
{
    for (SparseMatrix<int>::InnerIterator it(A,k); it; ++it)
    {
        std::cout << "(" << it.row() << ","; // row index
        std::cout << it.col() << ")\t"; // col index (here it is equal to k)
    }
}

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