matlab - Replicate vector and shift each copy by 1 row down without for-loop

Question

I would like replicate a vector N times to create a matrix with each copy shifted 1 row down. See image (first column is the vector 1 to 5). It would be great if this can be achieved without using for loop.

So far was able to to do this repmat(my_vector, 1, 5) to create an N x 5 matrix.

Answer 1

You can do it with toeplitz and tril;

a = [1 2 3 4 5]
out = tril( toeplitz(a) )

or

out = toeplitz(a, a*0)
%// out = toeplitz(a, zeros(size(a)) )  %// for large arrays

or if you don't mind some happy flipping:

out = flipud( hankel( flipud(a(:)) ) )