matrix indexing without loop

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mcdull hall 2018-8-2

评论： mcdull hall 2018-8-2

Hello,

Suppose I have two matrices, A and B:

 A = [2 3 1 4;
      1 4 1 3];
 B = [1 2 3 4;
      4 3 2 1];

Now I get the max indices for the matrix A:

[~,ind] = max(A,[],2);

I want to obtain the corresponding values of matrix B with ind:

 for ii = 1:2
  v(ii) = B(ii,ind(ii));
 end

How to get the values of B without a for loop?

Walter Roberson 2018-8-2

v = B(sub2ind(size(B), 1:size(B,1), ind))

mcdull hall 2018-8-2

By the way, it should be:

v = B(sub2ind(size(B), (1:size(B,1))', ind))

Thanks.

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