Indexing an 6 Dimensional array inside a for loop

Folks,

I am trying to call in the nth page of a 6D array from page 1 to 6. I am using the following code which is not looping through the 6 pages. nu is a 6D array.

for  k=1:6;

      for ii=1:size(nu,k);
          i=nu(ii);

            Calcs{ii}= A.*i ...etc

      end
end

I think my ii statement is not correct to index the nth page of 6D array. Any ideas? Thanks in advanced B

[dpb]

No, you're returning the size of the array nu in each dimension in turn.

Unless nu is a cell array, the dimensions in each direction are fixed; Matlab otherwise doesn't support jagged arrays.

The data for a given value of the sixth dimension of a 6D array would be a 5D array and addressed as

d5=nu(:,:,:,:,:,ii);   % the ii-th 6th-dimension of 6D array nu

You need to specify precisely which subsection you're intending to operate over.

[bugatti79]

Hi dpb,

Thanks for your input. I will note this see how it works. B

Answer 1

[David]

"Folks,

I am trying to call in the nth page of a 6D array from page 1 to 6. I am using the following code which is not looping through the 6 pages. nu is a 6D array.

      for  k=1:6;
          for ii=1:size(nu,k);
               i=nu(ii);
               Calcs{ii}= A.*i ...etc
          end
     end

I think my ii statement is not correct to index the nth page of 6D array. Any ideas? Thanks in advanced B"

I assume you are trying to loop through each of the elements along each dimension in the 6D array. If I am correct in my assumption, then I think the problem is as you say. Since nu is a 6D array, you must specify the dimension that is being indexed. In the line you correctly identified as the source of trouble, you are treating nu as if it were only a 1D array. For this to work, you could try reshaping nu into a 2D array, where the elements of each page span their own column. See the code below.

   NumDims = ndims(nu);
   numPages = size(nu,NumDims);

   %Initialize number of elements
   numpageElements = 1;
   for d=1:NumDims-1
       numpageElements = size(nu,d)*numpageElements;
   end
   %Reshape nu into a N x 6 column matrix.
   nunu = reshape(nu,numpageElements,numPages);

and then

    %Index through each page
    for p=1:6
        %Index through the elements on each page
        for ii=1:size(:,p)    
            i = nunu(ii,p);
            Calcs{ii} = A.*i ...etc
        end
    end

You can find more information relevant to your question here: http://www.mathworks.com/help/matlab/math/multidimensional-arrays.html#f1-86846

[bugatti79]

Hi David,

I have only seen your response now, thanks.

I forgot to mention that each page is an 18*9 matrix and 6 of these. Page 1 matrix, all the elements are the same numeric value. Page 2 matrix, all elements are of same value but different to page 1 and so on to page 6.

I am just repeating the set of calculations 6 times. I will look at the code later. Thanks for your help... B