Inserting a constant array in between each of the coloumns

Hi All,

Looking for a help on simple problem (New to Matlab)

Question:

I have an (M * N) matrix; now, I want to insert a constant array {1 * N} (say all 1's) in between each of the N columns.

Is there an easy way to do that.

Help is much appreciated.

Thanks a lot.

Answer 1

[Roger Stafford]

You can't place a 1 x N row vector between columns - it wouldn't fit. So I assume you really mean place it between rows. If that is what you mean, do this. Let the M x N matrix be A and the 1 x N array be B.

 A(1:2:2*M-1,:) = A;
 A(2:2:2*M-2,:) = repmat(B,M-1,1);

If by any chance you really want to place something between the columns, you would need an N x M matrix and an N x 1 constant array, that is, a column vector, and you would have to reverse the columns and rows in the above code.

[Harold Kumar]

Hi Roger,

Thanks for responding.

Not to worry. I managed to figure it out.

Here is the answer

----------

If you don't mind creating a temporary matrix, one way to do it would be to do the following:

old_matrix = rand(M,N); % Just for example

new_matrix = ones(M,2*N-1);

new_matrix(:,1:2:end) = old_matrix;

Note that for an arbitrary constant matrix, you could replace the second line with the following:

new_matrix = repmat(const_array,1,2*N-1);

[Roger Stafford]

You originally asserted that your constant array was 1 x N which is a row vector. I'm glad you changed to an M x 1 column vector here, which would indeed fit between columns.