How can I Improve the efficiency of the following code?

Hello I have this loop

id = unique(DATA(:,3));
rg = zeros(length(id),4);
for i = 1 : size(id,1)
 x = y(DATA(:,3)==id(i));
 rg(i,1) =  sum(sqrt((Y(x,4) - Xm(id(i),1)).^2 + (Y(x,3) - Xm(id(i),2)).^2 ))./size(x,1);
 rg(i,2) =  id(i);
 rg(i,3) =  Xm(id(i),1);
 rg(i,4) =  Xm(id(i),2);
end

It is a very slow process. Is there a way to improve it? In particular I would like to avoid the first line after the loop and do it with accumarray or similar function. Thank you.