MATLAB: Hi, I am trying to vectorize following for loop. Need some help?

for loopvectorization

    accumulator=zeros(numThetas,numRhos);
    accx_n=zeros(numEdgePixels,numThetas);
    for j=1:numThetas
    accumulator(j,:)=[0 histcounts(accx_n(:,j),rho)];
    end

Best Answer

This is a case where the 'old' histogram functions work better than the newer one. If you pass a matrix to histc, it returns the histogram of each column, exactly what you're doing right now with your loop.
You have to watch out that histc and histcounts do not behave exactly the same with regards to the edges (assuming rho is an edge vector), so you may have to modify your rho slightly.
accumulator = [zeros(size(accx_n, 1), 1), histc(accx_n, rho)]
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