Re-arranging array columns in alternating form

I would like to write a function:

function [Y]=AlternateColumns(X,n)

that takes an array X of the form:

and turns it into Y of the form:

In this example n=3, but it could be any number by which the entire number of columns is divisible. How is this possible without using a loop?

Answer 1

[Guillaume]

function Y = AlternateColumns(X, n)
    Y = reshape(permute(reshape(X, size(X, 1), [], n), [1 3 2]), size(X, 1), []);
end

Basically, reshape into a 3D array, swap dimensions 2 and 3 and reshape back into original shape.

[Saeid]

Brilliant! Thanks Guillaume!