Element-wise array replication in Matlab.

Question

Let's say I have a one-dimensional array:

a = [1, 2, 3];

Is there a built-in Matlab function that takes an array and an integer n and replicates each element of the array n times?

For example calling replicate(a, 3) should return [1,1,1,2,2,2,3,3,3].

Note that this is not at all the same as repmat. I can certainly implement replicate by doing repmat on each element and concatenating the result, but I am wondering if there is a built in function that is more efficient.

Answer 1

I'm a fan of the KRON function:

>> a = 1:3;
>> N = 3;
>> b = kron(a,ones(1,N))

b =

    1     1     1     2     2     2     3     3     3

You can also look at this related question (which dealt with replicating elements of 2-D matrices) to see some of the other solutions involving matrix indexing. Here's one such solution (inspired by Edric's answer):

>> b = a(ceil((1:N*numel(a))/N))

b =

    1     1     1     2     2     2     3     3     3

Answer 2

a = [1 2 3];
N = 3;

b = reshape(repmat(a,N,1), 1, [])