MATLAB: Is the pile-up of ones into the elements of a matrix parallelizable by parfor

Question

Hello,

Is there any way to do the following pile-up in matrix A using parfor?

A = zeros(1,J);
for i=1:n
  j = f(i); % f returns index j = 1,2,...J
  A(j) = A(j)+1;
end

Thanks in advance, Abi

Answer 1

You don't really want the A(j)=A(j)+1 inside the PARFOR, because that's not a data parallel operation. Presumably f(i) is the hard computation, in which case you could do,

    A=zeros(J,1);
    j=ones(n,2);
    parfor i=1:n
            j(i,1) = f(i); % f returns index j = 1,2,...J
    end
    A=accumarray(j,1,size(A)).'