retrieve value from specific location of matrix

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Hi suppose I have a matrix as follows:

m =

each row of m is the row,column index respectively.

And I have another matrix I.

I need to find the values of I of location m. How can I do that?

Is there anybody to help me? Thanks

Oleg Komarov 2011-6-1

use sub2ind to create from coordinates an index that points to the position.

m = [1     1
   3
   5
   2
   4
   1
   3
   5]
I = rand(5);
sub2ind(size(I),m(:,1),m(:,2))

To skip the overhead you can apply the engine of sub2ind directly (2d adaptation):

(m(:,2)-1)*size(I,1) + m(:,1)

Matt Fig 2011-6-2

You are using SUB2IND incorrectly. SUB2IND returns the indices for use into an array, not the indexed array. So, use it like this:

IDX = sub2ind(size(I),m(:,1),m(:,2)); % Create index vector

I(IDX) % Index into I with IDX.

yes this is correct.

Thanks.

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