Turning 1s to 0s in a logical vector when element distance between 1s is below threshold
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Hello,
I have a logical vector of 1.5 million elements. I need to look through the elements in the vector, and whenever I find a 1, I need to turn any potential subsequent 1s in the next N elements into 0s. While this would be easy to implement with a for loop, I'm struggling to figure out a more efficient way to do it.
Example:
If [ 1 1 0 0 0 0 1 0 1 0 0 0 1 ] is my vector, and my N threshold is 5, I want to turn that vector into [ 1 0 0 0 0 0 1 0 0 0 0 0 1 ].
Thank you in advance.
2 Comments
Chien-Han Su
on 3 Aug 2021
How about using find() to get indices of all trues, get distance from those indices by subtraction and turn true to false for those distance bellow threshold?
Accepted Answer
Jonas
on 4 Aug 2021
you can try the follwing, but i don't know if it is faster
H = [ 1 1 0 0 0 0 1 0 1 0 0 0 1 ]; eraseNAfter=5; Hstr=num2str(H); out=regexprep(Hstr,['1' repmat('.',[1 3*eraseNAfter])],['1' repmat(' 0',[1 eraseNAfter])]); asDouble=str2mat(out)
i am also sure the regexp could be written nicer
2 Comments
Jonas
on 4 Aug 2021
that's true, fast solition would be padding the array and removing the padded elements at the end
H = [ 1 1 0 0 0 0 1 0 1 0 0 0 1 1]; eraseNAfter=5; H=[H repmat(0,[1 eraseNAfter])]; Hstr=num2str(H); out=regexprep(Hstr,['1' repmat('.',[1 3*eraseNAfter])],['1' repmat(' 0',[1 eraseNAfter])]); asDouble=str2mat(out); asDouble((end-eraseNAfter+1):end)=[]
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