How to get back the original matrix?

4 views (last 30 days)
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?
  2 Comments
KSSV
KSSV on 25 Mar 2022
Already you have A...
Ammy
Ammy on 25 Mar 2022
Yes But by the reverse process?

Sign in to comment.

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,:);

Sign in to comment.

Categories

Find more on Shifting and Sorting Matrices in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!