how to velocize it (avoid loop is possible)
显示 更早的评论
E=[0 5 6 9 2;0 0 1 3 1;0 5 4 2 4]'
filtro=ones(size(E));
for i=1:width(E)
bu=find(E(:,i),1,'first');
filtro(1:bu,i)=0;
end
filtro
采纳的回答
E=[0 5 6 9 2;0 0 1 3 1;0 5 4 2 4]';
[~,I]=max(logical(E),[],1);
filtro=(1:height(E))'>I
更多回答（1 个）
I don't know if "velocize" (not a word) is supposed to mean "accelerate" or "vectorize". The two are not the same.
If you're looking for the fastest possible code, there's no way to know in advance because it depends on the sparsity of E. For very dense E, your loop will probably be faster than @Matt J's answer.
E=rand(5000,3000)>0.1;
tic
filtro=true(size(E));
for i=1:width(E)
bu=find(E(:,i),1,'first');
filtro(1:bu,i)=0;
end
toc
tic
[~,I]=max(logical(E),[],1);
filtro=(1:height(E))'>I;
toc
1 个评论
True, but be mindful of the flipside:
E=rand(5000,3000)>0.7;
tic
filtro=true(size(E));
for i=1:width(E)
bu=find(E(:,i),1,'first');
filtro(1:bu,i)=0;
end
toc
tic
[~,I]=max(logical(E),[],1);
filtro=(1:height(E))'>I;
toc
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