How to reduce the matrix

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Minnu 2013-5-2

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Sir,

I have a matrix of size 830x27,want to reduce the size to some ax27 using processpca?how to reduce it?

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Zhang lu 2013-5-2

在 MATLAB Online 中打开

a=rand(830,27);
n=30;
for i = 1:floor(size(a,1)/n)
           eval(['a' num2str(i) ' = a(n*(i-1)+1:n*i,:)'])
end
if mod(size(a,1),n)~=0
    I=floor(size(a,1)/n)+1;
    eval(['a' num2str(I) ' = a(n*i+1:end,:)'])
end

Jan 2013-5-2

编辑：Jan 2013-5-2

在 MATLAB Online 中打开

No, Zhang, do not do this. Using EVAL to hide an index in the name of a varibale is a really bad idea. This reduces the processing speed substantially, impedes debugging and required equivalently obtuse methods to access the variables later. It would be tremendously smarter to use an index as index (!):

a{I} = a(n*i+1:end, :)

See Answers: FAQ how can I create A1, A2, ... in a loop

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