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Maximizing along n-1 dimensions of an n-dimensional array without a for loop

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Brandon
Brandon on 12 Oct 2021
Commented: Jan on 13 Oct 2021
I have an n-dimensional array, VV, which I would like to maximize along all dimensions for each element in the first dimension. I would also like to obtain the associated linear indices so that I can evaluate related arrays at those locations. I have to do this a large amount of times, so I need to figure out a way to do this without a for loop.
Here is an example for an n=3 dimensional array, but with a loop:
VV=rand(10,10,10);
for ii=1:size(VV,1)
Vtemp = squeeze(VV(ii,:,:));
[V(ii) I(ii)] = max(Vtemp(:));
end
[~,ind] = ismember(V,VV);
Any help would be appreciated.

Accepted Answer

Jan
Jan on 12 Oct 2021
Edited: Jan on 12 Oct 2021
VV = rand(8, 9, 10);
for ii = 1:size(VV,1)
Vtemp = squeeze(VV(ii, :, :));
[V(ii), I(ii)] = max(Vtemp(:));
end
[~,ind] = ismember(V, VV);
ind
ind = 1×10
1161 12 293 1004 415 746 307 1228 479 620
s = size(VV, 1);
W = reshape(VV, s, []);
[maxV, Index] = max(W, [], 2);
ind2 = sub2ind(size(W), 1:s, Index.')
ind2 = 1×10
1161 12 293 1004 415 746 307 1228 479 620

More Answers (1)

Steven Lord
Steven Lord on 12 Oct 2021
VV=randi(1000, 5, 5, 5);
[values, locations] = max(VV, [], 1:ndims(VV)-1, 'linear');
check = [reshape(values, [], 1), reshape(VV(locations), [], 1)]
check = 5×2
904 904 984 984 973 973 981 981 975 975

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