使用Eigen的子矩阵和索引 [英] Submatrices and indices using Eigen

问题描述

我目前正在开发一个MATLAB项目，我想使用C ++和Eigen重新实现最重要的计算部分。
我想知道是否有一种方法来执行以下操作（MATLAB语法）：

I'm currently working on a MATLAB project and I'd like to re-implement the most computational-heavy parts using C++ and Eigen. I'd like to know if there's a way to perform the following operation (MATLAB syntax):

B = A(A < 3);

对于那些不熟悉MATLAB的人，上述命令初始化一个由

For those who are not familiar with MATLAB, the above-mentioned command initializes a matrix B made of the cells in A whose values are less than 3.

我从特征论坛，可以使用以下方式获取感兴趣的指数：

I've seen from a post on the Eigen forum that it's possible to obtain the indices of interest by using:

MatrixXi indices = (A.array() < 3).cast<int>();

我想要的是：

MatrixXd B = A(A.array() < 3);

谢谢。

推荐答案

目前有一个功能请求用于选择子 - 通过在Eigen BugTracker系统中索引的矩阵。因此，我怀疑这是可能的。

There currently is a feature request for selecting sub-matrices by indexing filed at the Eigen BugTracker system. Therefore, I doubt it will be possible that way.

我想到的唯一的解决方法是手动复制数据。不太好。

The only workaround I could think of is to copy the data manually. Not very nice though.

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