Using delay seq to shift data with different delay conditions

Hi! I have a matrix that has 10 columns and 50 rows. I want to introduce a delay in columns 2,3 and 4, and then again in columns 7,8,9 and 10. In column 2, I want a delay by one sample, in column 3 I want a delay by 2 samples, in column 4 I want a delay of 3 samples, and similarly in columns 7,8,9 and 10 I want delays of 4,5,6 and 7 samples. Is there a way I could use delayseq to automate this process? Thanks in advance!

[Sriram Tadavarty]

May i know what does delay mean here? Any small example for the situation.

[Zuha Yousuf]

Hi! Thanks for responding! By delay, I mean that I want to shift the samples down the columns. For example, suppose I had a matrix [2 3 4; 5 6 7; 8 9 10 ]. I want to shift the second and third columns down. For example, I want to shift the second column down by introducing 1 zero. I want to shift the third column down by introducing 2 zeros. Basically I want to do what circshift does, WITHOUT the circular aspect.

[Sriram Tadavarty]

So, to see if i understand correctly, you want the output to be [2 0 0;5 3 0;8 6 4;0 9 7;0 0 10], for the input matrix you placed. Am i right?

[Zuha Yousuf]

Yes exactly!

Answer 1

[Sriram Tadavarty]

Hi Zuha,

Here is the code for what is looked for:

a = rand(50,10);
shift = [0 1 2 3 0 0 1 2 3 4]; % Use the shift required for eah column
a1 = zeros(54,10);
a1(1:50,shift==0) = a(:,shift==0);
a1(2:51,shift==1) = a(:,shift==1);
a1(3:52,shift==2) = a(:,shift==2);
a1(4:53,shift==3) = a(:,shift==3);
a1(5:54,shift==4) = a(:,shift==4);

% Or this can be done through loop
a2 = zeros(size(a,1)+max(shift),size(a,2));
for i = 1:size(a,2)
    a2(shift(i)+1:size(a,1)+shift(i),i) = a(:,i);
end

Hope this helps.

Regards,

Sriram

[Zuha Yousuf]

Hi, that gives me this kind of matrix:

I see that columns 5 and 6 are both not being delayed. I want column 5 to not be delayed, and column 6 to be delayed. Is there any reason why this might be happening?

[Sriram Tadavarty]

Hi Zuha, In the shift variable provide the shift as non-zero for the sixth column and that would solve. The update to shift vector in the answer will help. Let me know if the sixth value changed from 0 to the value you want and you get the expected answer. And then, seeing the image below you don't want the number of rows to be changed, so after the loop, or after those calculations, update a1 = a1(1:50,1:10); and a2 = a(1:size(a,1),1:size(a,2)); Hope this helps.

[Zuha Yousuf]

Thanks so much! That helped.

Answer 2

[Zuha Yousuf]

Basically, something like this. The first column after the one not being delayed should always have one 0, the next always have two 0s and so on. I've attached a picture for clarity.