Efficiently calculating weighted distance in MATLAB

Question

Several posts exist about efficiently calculating pairwise distances in MATLAB. These posts tend to concern quickly calculating euclidean distance between large numbers of p

Answer 1

For r = 1 ("cityblock" case), you can use bsxfun to get elementwise subtractions and then use matrix-multiplication, which must speed up things. The implementation would look something like this -

%// Calculate absolute elementiwse subtractions
absm = abs(bsxfun(@minus,permute(A,[1 3 2]),permute(B,[3 1 2])));

%// Perform matrix multiplications with the given weights and reshape
D = reshape(reshape(absm,[],size(A,2))*wts(:),size(A,1),[]);