MATLAB: Ranking of vector with non-unique elements

MATLABnonuniquerankingvector

I need to perform fast ranking of the vector with non-unique elements, like in the following example:
F = [10.1 31.0 20.5 20.5 10.1] -> rankF = [3 1 2 2 3]
So far I am using the following code:
[~,~,iFu] = unique(F,'stable');
[~,iFs] = sort(F,'descend');
[~,iFs] = sort(iFs);
[~, ~, rankF] = unique(iFs(iFu));
But, I am not sure if this code is really effective. Is there any better (faster) way how to solve this problem?

Best Answer

So you want to order starting with the highest value?
F = [10.1 31.0 20.5 20.5 10.1]
[~, ~, rankF] = unique(max(F)-F)
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