Finding index to minimum values in 3D array

Question

KAE 2018-3-8

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/387213-finding-index-to-minimum-values-in-3d-array

评论： KAE 2018-3-9

I have a 3D matrix, and I would like to find the index to the minimum value along the 3rd dimension. In other words, I would like to replace the following loop with a faster operation:

A = rand(10,8,3);
indexToMinIn3rdDim = NaN*ones(size(A,1), size(A,2)); 
for iRow = 1:size(A,1)
    for iCol = 1:size(A,2)
        indexToMinInVector = find((squeeze(A(iRow,iCol,:))) == min((squeeze(A(iRow,iCol,:)))));
        indexToMinInVector = indexToMinInVector(1); % Only keep 1st index if the same min value occurs
        indexToMinIn3rdDim(iRow,iCol) = indexToMinInVector;
    end
end

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Answer 1

Rik 2018-3-9

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https://ww2.mathworks.cn/matlabcentral/answers/387213-finding-index-to-minimum-values-in-3d-array#answer_309148

在 MATLAB Online 中打开

The isequal function thinks the code below works.

A=rand(10,8,3);
[a,b]=min(A,[],3);
indexToMinIn3rdDim = NaN*ones(size(A,1), size(A,2)); 
for iRow = 1:size(A,1)
    for iCol = 1:size(A,2)
        indexToMinInVector = find((squeeze(A(iRow,iCol,:))) == min((squeeze(A(iRow,iCol,:)))));
        indexToMinInVector = indexToMinInVector(1); % Only keep 1st index if the same min value occurs
        indexToMinIn3rdDim(iRow,iCol) = indexToMinInVector;
    end
end
isequal(indexToMinIn3rdDim,b)