Finding index to minimum values in 3D array
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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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Accepted Answer
Rik
on 9 Mar 2018
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)
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