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getting the max and its positions from a 4D array

Asked by Sanghyun Lee on 11 Sep 2019
Latest activity Answered by Andrei Bobrov
on 12 Sep 2019
I'm trying to find a way to get the Max value from a 4D array and get the position of each of the max values of the 4D array so that I can trace back and get those positions from another 4D array. It would be great if someone can help me. Thanks in advance!
What I want is to get all the max values of each individual rows and columns and the 3rd dimension and its positions in the 4D.

  2 Comments

each of the max
along which dimension(s)? Are you expected a 3D, 2D, 1D, or scalar value in return?
well I guess the max dimensions is 3D but what I want to find is the 4D dimension/positions of each of the max values from which the dimension

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R2019a

2 Answers

Answer by Star Strider
on 11 Sep 2019

Try this:
A = rand(3,3,3,3); % Create Array
Amax = max(A(:)); % Maximum Value
Idx = find(A(:) == Amax); % Returns Linear Indices To All ‘Amax’ Values
[r,c,dim3,dim4] = ind2sub(size(A), Idx); % Returns Subscripts In Each Dimension For All ‘Amax’ Values

  12 Comments

yeah so the 3rd dimension is 1
oh wait I just realised this.
so is this why it wasn't working before?
Don't knoiw what before refers to.
oh wait I just realised this.
Really? you don't know what the size of each dimension is? Then, yes you're going to struggle writing your code if you don't know what is happening with your dimensions.
well no I knew it in my brain but my mind just realised

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Answer by Andrei Bobrov
on 12 Sep 2019

Maybe this:
[m,n,k,f] = size(totalDistance);% here k = 1
[~,ij] = max(totalDistance,[],4);
[I,J,K] = ndgrid(1:m,1:n,1:3);
F = repmat(ij,1,1,3);
finalPixels = imagesList(sub2ind([m,n,3,f],I,J,K,F)); % [m,n,3,f] size of imagesList

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