按特征向量对特征向量排序(关联排序) [英] Sorting eigenvectors by their eigenvalues (associated sorting)
问题描述
我有一个未分类的特征值向量和一个相关的特征向量矩阵.我想针对特征值的排序集对矩阵的列进行排序.(例如,如果eigenvalue [3]移至eigenvalue [2],我希望特征向量矩阵的第3列移至第2列.)
I have an unsorted vector of eigenvalues and a related matrix of eigenvectors. I'd like to sort the columns of the matrix with respect to the sorted set of eigenvalues. (e.g., if eigenvalue[3] moves to eigenvalue[2], I want column 3 of the eigenvector matrix to move over to column 2.)
我知道我可以通过 std :: sort
在 O(N log N)
中对特征值进行排序.不用滚动我自己的排序算法,如何确定矩阵的列(相关的特征向量)以及它们的特征值在排序时就遵循了?
I know I can sort the eigenvalues in O(N log N)
via std::sort
. Without rolling my own sorting algorithm, how do I make sure the matrix's columns (the associated eigenvectors) follow along with their eigenvalues as the latter are sorted?
推荐答案
通常只创建一个类似这样的结构:
Typically just create a structure something like this:
struct eigen {
int value;
double *vector;
bool operator<(eigen const &other) const {
return value < other.value;
}
};
或者,将特征值/特征向量放入 std :: pair
中-尽管我更喜欢 eigen.value
和 eigen.vector
something.first
和 something.second
.
Alternatively, just put the eigenvalue/eigenvector into an std::pair
-- though I'd prefer eigen.value
and eigen.vector
over something.first
and something.second
.
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