How to get back the original matrix?

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Ammy
Ammy on 25 Mar 2022
Answered: Torsten on 25 Mar 2022
A=[1 2 3 2;4 1 2 3;3 4 3 2;2 4 1 1];
>> R=[1 3 4 2];
>> B=A(R,:);
>> C=B(:)';
>> D=[1 0 0 1 0 1 0 1 0 1 0 0 1 1 0 1];
>> E=C(D==1);
Can we get back A?

Accepted Answer

Torsten
Torsten on 25 Mar 2022
A = [1 2 3 2;...
4 1 2 3;...
3 4 3 2;...
2 4 1 1]
R = [1 3 4 2];
B = A(R,:);
Rinv(R) = 1:numel(R);
A_recovered = B(Rinv,:)

More Answers (1)

Chunru
Chunru on 25 Mar 2022
A=[1 2 3 2;4 1 2 3;3 4 3 2;2 4 1 1];
% Reordering the rows of A is reversible
R=[1 3 4 2];
B=A(R,:);
% Straightening up the matrix into vector is also reversible
C=B(:)';
% Picking up part of the data is not reversible
D=[1 0 0 1 0 1 0 1 0 1 0 0 1 1 0 1];
E=C(D==1);
  1 Comment
Ammy
Ammy on 25 Mar 2022
@Chunru thank you
How the following can be
reversible ,
A=[1 2 3 2;4 1 2 3;3 4 3 2;2 4 1 1];
% Reordering the rows of A is reversible
R=[1 3 4 2];
B=A(R,:);

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