Optimal distance calculation for a data cube

I'm wondering if there's a better way to calculate my distance matrix?

function D = frame2frameDist(imageStack)

[h, w, c, l] = size(imageStack);

D = zeros(l);

for channel = 1:c
    for i = 1:l
        for j = i:l
          D(i,j) = D(i,j) + norm(imageStack(:,:,channel,i)-imageStack(:,:,channel,j));
      end;
    end;
end;
D = triu(D)+triu(D,1)';

Is there a way to do this without iteration?

[John BG]

have you tried

     for i = 1:l
          for j = i:l
            D(i,j) = D(i,j) + norm(imageStack(:,:,:,i)-imageStack(:,:,:,j));
        end;
      end;

can you submit a sample of frames and channels?

also, functions bsxfun and arrayfun may have a way to combine the norm() and rid loops i and j.

There is an expert in this forum called Andrei Bobrov who showed me how to use bsxfun, may be you could ask him.

Answer 1

[Walter Roberson]

Possibly reshape to rows, and then pdist() ?