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From: Sean on 12 May 2010 15:50
"Kuroro Lam" <v5lam(a)engmail.uwaterloo.ca> wrote in message <hseuk0$9c8$1(a)fred.mathworks.com>...
> I want to create an array that looks like this:
>
> ids = [1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6 ... N, N, N, N]


>>ids = kron(1:N,ones(1,4))
From: Matt J on 12 May 2010 16:30
"Kuroro Lam" <v5lam(a)engmail.uwaterloo.ca> wrote in message <hseuk0$9c8$1(a)fred.mathworks.com>...

> I want to create an array that looks like this:
>
> ids = [1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6 ... N, N, N, N]
=======

Seems like a bad idea as it generates a lot of redundant data. What do you need it for?
From: Loren Shure on 13 May 2010 07:00
In article <hseuk0$9c8$1(a)fred.mathworks.com>, v5lam(a)engmail.uwaterloo.ca
says...
> I want to create an array that looks like this:
>
> ids = [1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6 ... N, N, N, N]
>
> Right now I'm using a for loop between 1 and N and concatenating each set of numbers on to the array.
>
> ids = []
> for i=1:N
> ids = [ids ones(1,6)*i]
> end
>
> This works perfectly fine, I'm just wondering if there might be better way of doing it.
>

Do you really need this expanded array, or could you work with 1:N and
do what you need with bsxfun? If so, it could be more memory-efficient.

--
Loren
http://blogs.mathworks.com/loren
http://matlabwiki.mathworks.com/MATLAB_FAQ
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