Matrix rows and columns swapping

179 vues (au cours des 30 derniers jours)
Rakesh Belchandan
Rakesh Belchandan le 11 Nov 2019
Commenté : Walter Roberson le 24 Fév 2022
I want to completely change rows and column simultaneously (please see the picture attached)
Is there a function which can do this?
Thanks,
Rakesh
  2 commentaires
Logan Hall
Logan Hall le 24 Fév 2021
For anyone who is looking to swap an array:
Array = Array.';
btw sorry for reviving a dead thread.
Walter Roberson
Walter Roberson le 24 Fév 2021
That does not solve the user's problem at all. The user needs the upper left corner (a 1 in their data) to go to the middle, but using .' would leave the upper left corner exactly where it is.

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Réponses (3)

Walter Roberson
Walter Roberson le 11 Nov 2019
There is no function that can do that simultaneously, at least not the first time.
For any given row and column exchange pattern, it is possible to pre-process the pattern so that doing the same exchange for multiple different arrays would take place simultaneously for that one matrix. Something like
temp = preprocess_exchange(rows_to_exchange, columns_to_exchange);
newA = A(temp);
newB = B(temp);
where preprocess_exchange is a function that would need to be written.
  2 commentaires
Walter Roberson
Walter Roberson le 12 Nov 2019
I should correct myself: you can do this with indexing.
>> A = [1 2 3;4 5 6;7 8 9]
A =
1 2 3
4 5 6
7 8 9
>> A([2 1 3],[2 1 3])
ans =
5 4 6
2 1 3
8 7 9
Rakesh Belchandan
Rakesh Belchandan le 12 Nov 2019
Thanks. That works for me.

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Akira Agata
Akira Agata le 12 Nov 2019
I don't think rows and column can be randomly changed simultaneously.
There should be at least 2 steps, like this:
% Input 3-by-3 matrix
A = reshape(1:9,3,3)';
% Randomize rows and columns
A = A(randperm(3),:);
A = A(:,randperm(3));

Franco Garcia
Franco Garcia le 24 Fév 2022
Modifié(e) : Franco Garcia le 24 Fév 2022
You can actually do that easily with just proper indexing. According to the example in the attachment:
A=[1,2,3;4,5,6;7,8,9] % The input in your example
A = 3×3
1 2 3 4 5 6 7 8 9
B=A([2,1,3],[2,1,3]) % Your expected output
B = 3×3
5 4 6 2 1 3 8 7 9
Regards!

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