MATLAB: Using matrix index coming from max function to get values from another matrix

matrix indexingmax function

Dear All, I have the following problem:
A = randn(5,5);
B = randn(5,5);
C = randn(5,5);
D = cat(3,A,B,C);
E = randn(5,5,3);
[M,I] = max(D,[],3);
How to use the index matrix I to get respective elements from matrix E ? It means for every combination of i and j I want to take the value of E(i,j,:) whose index is given by the value of I(i,j).
I will be grateful for any comments!

Best Answer

This seems to work:
A = randn(5,5);
B = randn(5,5);
C = randn(5,5);
D = cat(3,A,B,C);
E = randn(5,5,3);
[M,I] = max(D,[],3);
IL = sub2ind(size(D), cumsum(ones(size(D,1)),1), cumsum(ones(size(D,2)),2), I);
Check = D(IL);                                      % Check To Be Sure Indexing Is Correct
Result = E(IL);
The ‘Check’ assignment demonstrates that the indexing reproduces ‘M’. It is not necessary for the code, and can be deleted.
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