Fast way to replicate array

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Thang Bui
Thang Bui 2015-4-28
编辑： Andrei Bobrov 2015-4-28
I have a matrix W of size ExF, and I have a matrix D of size NxFxNxE where D(n,:,n,:) = W'
Is there a fast way to replicate W to form D without having to loop through N
Thanks!

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采纳的回答

Mohammad Abouali
Mohammad Abouali 2015-4-28
编辑：Mohammad Abouali 2015-4-28
w=[1 2; ...
3 4; ...
5 6];
N=5;
E=size(w,1);
F=size(w,2);
D=repmat(reshape(w',1,F,1,E),N,1,N,1);

更多回答（2 个）

Jan
Jan 2015-4-28
You want to obtain W from D?
W = squeeze(D(k, :, k, :)).'
  1 个评论
Thang Bui
Thang Bui 2015-4-28
编辑：Thang Bui 2015-4-28
Nope, obtain D from W, the loop version looks roughly like this
D = zeros(N,F,N,E);
for n = 1:N
D(n,:,n,:) = W'; % perhaps need permute here
end

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Andrei Bobrov
Andrei Bobrov 2015-4-28
编辑：Andrei Bobrov 2015-4-28
i1 = bsxfun(@plus,[0;N]+1,(0:N-1)*(2*N+1));
i2 = bsxfun(@plus,i1,reshape((0:F)*i1(end),1,1,[]));
D = zeros(N,F,N,E);
D(i2) = permute(repmat(W,[1,1,N]),[2,3,1]);

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