Finding index of minimum of a subset of an array

I want to find the index of the greater array for a subset within that array.

Example:

       A=[2 3; 1 8; 2 6; 3 1;]
       [row, col]=find(min(A([2 4], 2)));

This will compare the numbers 8 and 1, and I want to retrieve the index of A for the value of 1. Instead what this will output now is 2, since the subset being considered is [8 1]. What I want is for [row col] to equal [4 4], because this is the index in A where the minimum of the subset is located.

Any suggestions? Thanks,

[Alfonso]

I'm not sure if I have understood it correctly, you mean finding the minimum value for each row?

[Matt J]

What I want is for [row col] to equal [4 4], because this is the index in A where the minimum of the subset is located.

I think you mean [4,2].

Answer 1

[Matt J]

B=A;
subset=false(size(A)); 
  subset([2,4],2)=true;

B(~subset)=inf;

[row,col] = find(B==min(B(:))),

Answer 2

[Matt J]

Another way. This method is probably more efficient if you need to do this repeatedly with a large array A, but small subsets.

subset={[2,4],2}; %example

lookup=reshape(1:numel(A),size(A));

T=lookup(subset{:});
[minval,loc]=min( A(subset{:}) );

[row,col]=ind2sub(size(A), T(loc) )