Populating a matrix with predetermined values

I have a N x N matrix which I have defined as X, I have another matrix that contains values I would like to populate my matrix X with.

For example, if X is a 3 x 3 matrix and A is the matrix below:

A =

     3    15
     4    16
     5    17
     6    18
     7    19

How do I populate the matrix X with the values in the second column of A where the first column is the position in the matrix X. i.e I would like the final matrix X to be

X =  0  0 15
    16 17 18
    19  0  0

Thank you.

Answer 1

[James Tursa]

X = zeros(N,N);
X(A(:,1)) = A(:,2);
X = X';

[Alice Stembridge]

Hi James, thank you for that. Would I do the same to populate a 3 x 3 x 3 matrix?

[James Tursa]

The example you gave works with linear indexing into a 2D matrix. For a 3D array you will have to give a short example of where the elements would go before we can answer how to do it and whether linear indexing will work.

[Alice Stembridge]

Hi James, Sorry I did not see that you had commented again. I think I have figured it out now. Thank you though.