How to create 3D array out of 2D, with one row step without using for loop?

Hello,

Lets say I have 2D array x(1100x5), n1=1100,d=501 and w=500. I can create 3D array, with one row step using for loop, however it is very slow working with bigger arrays:

   for k=1:n1-d
a(:,:,k)=x(d-w+k-1:d+k-2,:);
  end

What would be the way without using for loop?

[John D'Errico]

It is slow mainly because you do not understand the importance of preallocating your array, thus a. When you grow an array as you did, you force MATLAB to reallocate that memory each time in the loop. This gets slow, because the memory needed increases in size each time through.

[Mantas Vaitonis]

Thank You for Your answer, regarding preallocation, I do this a=zeros(500,5,599,'gpuArray'); and accordingly when working with bigger arrays, but its little help.

Answer 1

[Matt J]

 xt=x.';
 idx=(d-w+1:d-2).' + (1:n1-d);

 a=permute( reshape(  xt(:,idx(:))   ,5,[],n1-d)    ,[2,1,3]) ;

[Mantas Vaitonis]

Greate, thank You.