C ++ Armadillo生成给定vec或矩阵的索引uvec，而无需循环它 [英] C++ Armadillo Generate Indices uvec of a given vec or matrix without looping it

问题描述

Hellos伙计们，

Hellos guys,

我的问题可能很明显，但是我没有在其他帖子或《犰狳文档》上找到答案.

My question might be obvious but i didn't find answers on other posts or Armadillo Doc.

我想创建一个向量B(在我的情况下为arma :: uvec)，并使用给定向量A的每个索引.因此所需元素为(0:A.n_elem-1 ).我可以循环播放，但是我需要最佳地优化时间，所以我只想知道是否可以不循环播放.最后一点，我想避免使用C ++ 11.

I would like to create a vector B(arma::uvec in my case), with every index of a given vector A. So the needed elements are (0:A.n_elem-1). I could loop it, but I need to optimize time at its best, so I just want to know if I can generate it without looping it. Last point, I would like to avoid C++ 11.

谢谢您的时间.

我确实使用过find_finite(X)来生成索引vec，因为我的数据都是有限的，我仍然不知道正确的方法.

EDIT 1 : I did use find_finite(X), to generate my indices vec, because my datas are all finite, i still don't know the proper way to do it.

推荐答案

我不太了解with every index of a given vector A，但是如果您需要B来包含0:A.n_elem-1，则可以执行以下操作:

I don't quite understand with every index of a given vector A, but if you need B to contain 0:A.n_elem-1, you can do:

vec B = regspace<vec>(0, A.n_elem-1)

上面的代码等效于MATLAB中的B = 0:length(A)-1.

Above code is equivalent to B = 0:length(A)-1, in MATLAB.

希望有帮助.

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