Extending an order in a vector

I have a vector that provides me with a strict order of n number. If n is 5, for example, I type

y=randperm(5)

and I get something like

1 3 5 4 2

I want to scale this order by a factor of x. If x=3, I would like to get

1 2 3 7 8 9 13 14 15 10 11 12 4 5 6

Is there an easy way to do this that I am missing? I know that

reshape(repmat(y,x=3,1),1,[])

creates

1 1 1 3 3 3 5 5 5 4 4 4 2 2 2

and then I can add 1 to 3 using a loop, but surely there is something faster that I am missing.

[Josué Ortega]

I have another question. The command you suggested gives me

1 2 3 7 8 9 13 14 15 10 11 12 4 5 6

is there a way to get the order of each group randomly?

So that I could get

3 1 2 9 7 8 13 14 15 11 10 12 4 6 5

Any ideas are most welcomed.

[James Tursa]

result = cell2mat(arrayfun(@(y)randperm(x)+(y-1)*x,y,'uni',false));

Answer 1

[James Tursa]

One way:

>> result = cell2mat(arrayfun(@(y)x*y-x+1:x*y,y,'uni',false))
result =
     1     2     3     7     8     9    13    14    15    10    11    12     4     5     6

[Josué Ortega]

Many thanks for your kind answer! Just one more question: how do I invert this? Suppose I have "result", how do I get the original order?

Thanks

[James Tursa]

Do you also know x? And using result and x want to get y?

[Josué Ortega]

exactly

[Josué Ortega]

got it, apologies for the silly question