how rearrange data in a matrix?

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Ved
Ved on 19 Oct 2013
Commented: Andrei Bobrov on 20 Oct 2013
I have a data as:
data=[1 2 3 4 5 6 7 8];
I need a new data matrix (4 x 8),like this:
new_data =[ 1 2 0 0 0 0 0 0
0 0 3 4 0 0 0 0
0 0 0 0 5 6 0 0
0 0 0 0 0 0 7 8 ]
How to do it using a FOR loop ? Any help?

Accepted Answer

Azzi Abdelmalek
Azzi Abdelmalek on 19 Oct 2013
Edited: Azzi Abdelmalek on 19 Oct 2013
data=[1 2 3 4 5 6 7 8];
n=numel(data);
R=zeros(n/2,n);
R(:,1:2)=reshape(data,2,[])';
out=cell2mat(arrayfun(@(x) circshift(R(x+1,:),[ 0 2*x]),(0:3)','un',0))
%or
data=[1 2 3 4 5 6 7 8];
n=numel(data);
out=zeros(n/2,n);
out(sub2ind(size(out),repmat((1:n/2),2,1),reshape(1:n,2,[])))=data
%or
EDIT
n=numel(data);
a=[reshape(data,2,[]) ;zeros(n,n/2)];
a=a(:);
a(end-n+1:end)=[];
out=reshape(a,n,n/2)'
  2 Comments
Ved
Ved on 19 Oct 2013
@Azzi:
Could you please explain the line which is using cell2mat() in your first code.

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More Answers (1)

Andrei Bobrov
Andrei Bobrov on 19 Oct 2013
Edited: Andrei Bobrov on 20 Oct 2013
a = num2cell(reshape(data,1,2,[]),[1 2])
out = blkdiag(a{:});
or
out = kron(eye(4),[1 1])*diag(data);
or
out = reshape(permute(repmat(eye(4),[1,1,2]),[1 3 2]),4,[])*diag(data);
  2 Comments

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