How to make a for faster?

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Oliver Lestrange
Oliver Lestrange 2020-8-29
编辑： Bruno Luong 2020-8-29
Hi,
I've the following code.
ix = ismember(idx_x(:),x(:));
iy = ismember(idx_y(:),y(:));
minimum = min(ix,iy);
for idx_=1:18:length(iy)
for idx=1:18:length(ix)
if minimum(idx)==1
%index =[index;idx];
altura_raio_direto = [altura_raio_direto; heights(idx)];
% saber indices de heights que fazem parte do bresenham
end
iii = iii+1;
disp(iii);
end
end
heights is an array of 90 000 positions, as well as iy and ix.
How can I make this faster?
Thanks!
  1 个评论
Bruno Luong
Bruno Luong 2020-8-29
编辑：Bruno Luong 2020-8-29
You must think what is your double-loops are looping on. As long as you still see the need of double-loop you are completely off of understanding ISMEMBER and linear indexing.

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回答（2 个）

KSSV
KSSV 2020-8-29
idx_=1:18:length(iy) ;
idx=1:18:length(ix) ;
if min(idx)==1
altura_raio_direto = heights(idx) ;
end
altura_raio_direto = repmat(altura_raio_direto,1,length(idx_1)-1) ;
  1 个评论
Oliver Lestrange
Oliver Lestrange 2020-8-29
I am sorry, I forgot to mention what minimum is.
I've already edit the post.
minimum = min(ix,iy);

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Bruno Luong
Bruno Luong 2020-8-29
编辑：Bruno Luong 2020-8-29
ix = ismember(idx_x(:),x(:));
iy = ismember(idx_y(:),y(:));
ixy = ix & iy;
idx = 1:18:size(ixy,1);
altura_raio_direto = heights(idx(ixy(idx)));
%altura_raio_direto = repmat(altura_raio_direto,length(idx,1); % outer loop concatenate the same thing over and over

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