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

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Shakir Hussain
Shakir Hussain 2018-10-20
评论： Shakir Hussain 2018-10-26
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

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采纳的回答

Walter Roberson
Walter Roberson 2018-10-20
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.
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Walter Roberson
Walter Roberson 2018-10-23
I do not know what the individual entries in your cell array are intended to mean.
Shakir Hussain
Shakir Hussain 2018-10-25
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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更多回答（1 个）

Bruno Luong
Bruno Luong 2018-10-20

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

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