Divide the matrix randomly, based on columns

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Joana 2019-12-11

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评论： Rik 2019-12-11

Hi

I have a matrix x of size 78000x204. I need to divide it into nonoverlapping but random 70:15:15 percent of the data, based on number of columns.

Any help, how to do that.?

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Answer 1

Rik 2019-12-11

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You mean like this?

fractions=[70 15 15];
x=rand(78000,100);%use 100 to show the split is indeed 75:15:15
groups=cell(size(fractions));%pre-allocate output
f=fractions/sum(fractions);
f=[0 cumsum(f)];
r=randperm(size(x,2))/size(x,2);
for n=1:numel(groups)
    L= r>f(n) & r<=f(n+1);
    groups{n}=x(:,L);
end

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Joana 2019-12-11

Yes, but i'm not sure if it's dividing the data randomly and nonoverlapping.?

I can't figure it out as it's a long data with 78000x204.

Rik 2019-12-11

Because randperm is generating the indices, this is guaranteed not to result in overlapping groups. Unless there are columns in your data that are equal to eachother, there is not be any match between the groups.

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