swap elements in a matrix

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Hello i want to swap elements in a matrix.I want to do it to elements of the same row and to elements of differents rows. Please help.Thank you
Giannakis Stoukas
Giannakis Stoukas on 20 Mar 2015
To be more specific i want to execute local search to a matrix like this one
A=[1 4 7 16 32 48 1;
1 5 6 23 1 0 0;
1 9 31 8 2 1 0;
1 11 19 66 1 0 0]
The the elements of the matrix are arcs(for example 9-31 is the arc between nodes 9 and 31),so i want to make enough exchanges to reduce the cost.I can do exchanges of the same row like the 9 with 31 and i will the 3 row 1 31 9 8 2 1 0 and the other rows as they were,and i can do exchanges of different rows like the node 9 with the node 11. Is there any command to swap,or i have to use temp variables?

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Accepted Answer

the cyclist
the cyclist on 20 Mar 2015
Edited: the cyclist on 10 May 2018
% A matrix:
A = magic(3);
% Swap the first and second elements of the first column:
A([1 2]) = A([2 1])
% Swap the first and second elements of the third column:
A([7 8]) = A([8 7])
% Swap the first and third elements of the first row:
A([1 7]) = A([7 1])
Note that I needed to take advantage of linear indexing.
the cyclist
the cyclist on 10 May 2018
Oops, there were actually a couple confusing typos in my post. I have edited to correct them. Thanks for pointing that out.

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More Answers (1)

Ahamed Tuani
Ahamed Tuani on 13 Nov 2017
I have been looking into local search as well. Giannakis, I know its quite q while ago but have you figure out how to do it?
The cyclist and fellow members, I have a question..say the path is 1-31-9-2-10-1..I want to swap 9 and 2 so that the new path will be 1-31-2-9-10-1. How can I do this? Tried indexing (maybe a dumb way) i.e init_tour((1:2):(4):(3):6) to get the new tour but its not working. Any help will be greatly appreciated. Thanks.


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