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Why 'for loop' is very slow even working on server

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My 'for loop' looks like
iwant = cell(a,b);
for i =1:17
c = data(:,:,i);
for j = 1:b
idx = inpolygon(X(:),Y(:),S(j).X , S(j).Y);
iwant{i,j} = c(idx);
end
end
Where a =17,c = 420*940, X = 420*940, Y = 420*940 and b = 1*1 which is polygon and its size is (shape_area 56.4087, x= 1*679340, y = 1*679340).
This for loop is taking very long time even days, so how could I execute it in minimum time
Thank you in advance for any kind of help

Accepted Answer

Walter Roberson
Walter Roberson on 20 Oct 2018
The idx results are the same for all i values for a given j. Loop over j precomputing them and then loop over i pulling out the appropriate entries.
  9 Comments
Shakir Hussain
Shakir Hussain on 25 Oct 2018
The test data has attached here, which I want to convert into a matrix having 17 rows and columns according to data size. I was facing problem to attached sample data here from last few days

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More Answers (1)

Bruno Luong
Bruno Luong on 20 Oct 2018

As I mention in another thread you can get on FEX that can be 100 times faster than MATLAB inpolygon, let alone the newy polyshape

  7 Comments

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