Matrix rows and columns swapping

Question

Rakesh Belchandan 2019-11-11

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评论： Walter Roberson 2022-2-24

matrix_conversion.PNG

I want to completely change rows and column simultaneously (please see the picture attached)

Is there a function which can do this?

Thanks,

Rakesh

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Logan Hall 2021-2-24

For anyone who is looking to swap an array:

Array = Array.';

btw sorry for reviving a dead thread.

Walter Roberson 2021-2-24

@Logan Hall

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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Answer 1

Walter Roberson 2019-11-11

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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.

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Walter Roberson 2019-11-12

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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 2019-11-12

Thanks. That works for me.

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Answer 2

Akira Agata 2019-11-12

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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));

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Rakesh Belchandan 2019-11-12

Thanks.

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Answer 3

Franco Garcia 2022-2-24

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编辑：Franco Garcia 2022-2-24

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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