Extract indices from other matrix corresponding to the minimum

Question

KostasK 2022-2-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1644750-extract-indices-from-other-matrix-corresponding-to-the-minimum

编辑： Matt J 2022-2-7

I currently have a matrix in which I want to determine the column which corresponds to the minimum of each row, which I can do the following way:

Mat = rand(30, 2) ;
[~, min_idx] = min(Mat, [], 2, 'linear') ;
[~, col] = ind2sub(size(Mat), min_idx) ;

Following that, I would like to use col, to extract the corresponding 3rd dimension in another matrix X:

X = rand(30, 3, 2) ;
Xmin = X(:,:,col) ;

For Xmin I would expect to get a 2D matrix, where each row corresponds to the index col in the 3rd dimention extracted from X, however that is not the case for some reason. Do you know how I could accomplish the above?

Thanks for your help in advance.

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Answer 1

Matt J 2022-2-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1644750-extract-indices-from-other-matrix-corresponding-to-the-minimum#answer_890575

编辑：Matt J 2022-2-7

在 MATLAB Online 中打开

Mat =  rand(30,2);
X = rand(30, 3, 2) ;
[~, min_idx] = min(Mat, [], 2, 'linear') ;
Xp=reshape( permute(X,[1,3,2]),[],3);
Xmin=Xp(min_idx,:)
Xmin = 30×3
    0.0712    0.3075    0.8858
    0.6488    0.0418    0.7136
    0.9145    0.4471    0.9905
    0.1935    0.1567    0.1708
    0.1016    0.3393    0.3916
    0.8534    0.8261    0.4123
    0.2960    0.7503    0.8993
    0.1845    0.9356    0.2080
    0.7731    0.7444    0.5096
    0.5429    0.7494    0.9430