How to split array in n part every m points ?

Hi everyone,

This question is very frustrating. 3 months ago, I found, 'by chance', a function that I didn't need, and now I need it and I don't remenber the name...

For approximately 4 hours i searched this function, and it seems I don't have 'luck' anymore

On a matrix of 1*n, this function split this matrix into vectors of p values with a step of r .

For example :

A = [ 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 ];

B = function(A,p,r) ; returned B = [ 1 2 3 ; 2 3 4 ; 3 4 5 ; 4 5 6 ; ... ; ... ;17 18 19 ; 18 19 20 ]

assuming p = 3 and r = 1

Does anyone know the name of this function ?

There was no iteration, or loop, it was just a simple function but very powerfull for a specified purpose : - )

Thank you in advance to help me to get my lucky charm back

Answer 1

[Matt J]

I don't know of any built-in function that will do that, but it is easy to implement:

function B=foo(A,p,r) 
  N=numel(A);
  idx=(0:r:N-p).'+(1:p);
  B=A(idx);
end

[Charles Herman]

" I don't know of any built-in function that will do that, but it is easy to implement: "

Maybe I dreamt :-/ but I was pretty sure that it exists.

Nevertheless, I'll try your code and "yes!" it's a deal :)

Mine was based on a 'for loop' and it took 0.059481 seconds while yours only took 0.005267 seconds.

In the few days I will probably find this secret function one more time, in that case I'll leave it as a comment.

Thank you a lot for your help

[Matt J]

You're welcome, but please Accept-click the answer if it addresses your question.

[Charles Herman]

Oupsi : )

Now it's done

Have a nice day