Program takes long time to run

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Pat 2012-12-10

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https://ww2.mathworks.cn/matlabcentral/answers/56172-program-takes-long-time-to-run

I have a code below,but it takes long time to run,please assist how to make it run faster
for k = 1:(length(dirlist))
img = imread([pathname, dirlist(k).name]);
flatImg =img(:); 
idx = k_means(3,flatImg); 
N{k}=(reshape(idx,size(img,1),size(img,2)));
end
i have 7 images

please assist

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Walter Roberson 2012-12-10

How big are your images? Are your images RGB (truecolor) or grayscale?

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Answer 1

Image Analyst 2012-12-10

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Use the code profiling tool or insert tics and tocs into the code to find out what's taking so long. It's probably k_means. You might be able to get very close to the same results in 1/16 the sime if you just subsample your image by a factor of 4 in both directions. Please state how long is "a long time". Is it several hours, minutes, or seconds? I've seen some people say 0.05 seconds is too long and others say days is too long and would be happy to get it down to a few hours.

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Pat 2012-12-10

it nearly takes 20 minutes ,if i use k means i get error,empty clusters ,thats y i have used k_means.

Kelly Kearney 2012-12-10

在 MATLAB Online 中打开

You can eliminate the error via the 'EmptyAction' parameter with kmeans; I'm not familiar with your alternative k_means function but perhaps reverting to

kmeans(... , 'EmptyAction', 'drop')

might help?

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