0 个投票

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

2 个评论
显示 无 隐藏 无

Adam
Adam 2015-3-20
An example would be useful, although the usual method for swapping elements is to use a temporary variable to store one while you copy the other over the top of it and then copy from the temporary variable into the 2nd location.
Giannakis Stoukas
Giannakis Stoukas 2015-3-20
编辑：the cyclist 2015-3-20
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?

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

the cyclist
the cyclist 2015-3-20
编辑：the cyclist 2018-5-10

3 个投票

% 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.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

Giannakis Stoukas
Giannakis Stoukas 2015-3-20
Thank you for your respond.It is not exactly what i want to do.I have answerd previous what i want.More specifically i have a matrix of arcs and i want to execute local search exchanges to minimize the cost (that i have in different variable).
the cyclist
the cyclist 2015-3-20
You can use my technique, as long as you understand the linear indexing page I cited.
For example, to swap 9 and 31 in your example, use
A([11 7]) = A([7 11])
The number 9 is in the 7th position (using linear indexing), and the number 31 is in the 11th position.
YANAN ZHU
YANAN ZHU 2018-5-9
A([1 7]) = A([7 1]) actually swap the first and third elements of the first row, not "Swap the first and second elements of the first row"
the cyclist
the cyclist 2018-5-10
Oops, there were actually a couple confusing typos in my post. I have edited to correct them. Thanks for pointing that out.

请先登录，再进行评论。

更多回答（1 个）

Ahamed Tuani
Ahamed Tuani 2017-11-13

0 个投票

Hi,
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.

类别

在 帮助中心 和 File Exchange 中查找有关 Direct Search 的更多信息

标签

Community Treasure Hunt

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

Start Hunting!

Translated by