How Can I randomly select 20% of my array elements AND save their indices (row,column) ?
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I have a matrix A with n points.
A = [230,30,40,40,80;40 40 30 80 230;40 40 40 230 80]; n=numel(A);
How can i now randomly select a percentage of the points (example p=20% of n) ?
The output should be a new matrix with these random elements. AND another array that tells me "which" elements(row, column) were selected.
Any help appreciated :)
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Jan
2017-7-19
编辑:Jan
2017-7-19
A = [230,30,40,40,80;40 40 30 80 230;40 40 40 230 80];
n = numel(A);
Index = randperm(numel(A), ceil(numel(A) * 0.20));
[Xp, Yp] = ind2sub(size(A), Index);
Selected = A(Index);
This chooses 20% of the values randomly and replies the values in Selected and the indices in Xp, Yp.
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ES
2017-7-19
A = [230,30,40,40,80;40 40 30 80 230;40 40 40 230 80];
n=numel(A);
B=reshape(A, 1, n); %1-D array
p = randperm(n);%random permutation of numbers till n
k = p(1:ceil(numel(p)/8));%Very poor algo for 1st to 20% of elements. You can improve here
C=B(p);%Target Matrix
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