Specific pseudo-randomised number generator.

I am currenlty running an experiment that reads from a text file that requires specific formatting.

I need to create a matrix composed to two colunms (e.g. 200 x 2). One column needs to consist of only 1's and -1's in a pseudorandomised order with no more than three repeats of the same number consequatively and each number to appear an equal amount of times. The other column needs to be composed of 0's and 1's, where the 1's match up with the 1's in the first column and the 0's match up with the -1's.

I was wondering if this would be simple to do in Matlab and/or if anyone could help me out?

Cheers.

Answer 1

[Bruno Luong]

n = 2*ones(2,50);
for k=1:2
    p=randperm(50,32); % you might randomize 32 as well (must be even number in [0,50]);
    n(k,p)=repmat([1 3],1,length(p)/2);
end
A=repelem(repmat([-1 0; 1 1],50,1),n(:),1)

[Matt W]

Hi Bruno,

Thanks for this, works great! What is the exact purpose of 32 and what would be the effect if it were to be changed to a bigger or smaller number?

Thanks again.

[Bruno Luong]

32=2*16

Meaning I want to generate 16 sequence of 1-length, 16 sequences of 3-length and then 18 (=50-32) sequences of 2-length (so the total length of all sequences is 100).

If you reduce the parameter 32 you'll have more sequences of length 2 than 1 and 3. And vice versa.

[Matt W]

Great, thank you. Last thing; I then assume that if I require additional rows (e.g. 400 rather than 200) I would change the 50 to 100 and would need to adjust the parameter 32 accordingly e.g. 64 or 66?!

Thanks.

[Bruno Luong]

Correct.