swap columns of a matrix

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Rasmus
Rasmus on 25 Feb 2014
Hello guys/girls
How do i swap columns??
I have this
k_minus =
-46 -43 -26 -14 7 19 11 32 39 45 45
0 -4 -7 -7 -44 -44 -7 -7 -15 -15 0
and I want the columns to be in opposite order - How do I do this? and can do this in one go?
  1 Comment
Keerthi Krishna PARVATHANENI
Easy way is to swap the coloums based on the positon
For example:
A=[10 20 30;
40 50 60];
swap the coloum 1 to 2 can be done by
A(:,[2 1 3])
ans =
20 10 30
50 40 60
Exact approach can be adopted ot swap rows
A([2 1],:)
ans =
40 50 60
10 20 30
I think, this can be easy way with minium code.
Enjoy :)

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Accepted Answer

Thomas
Thomas on 25 Feb 2014
Edited: Thomas on 25 Feb 2014
You could also use
out= fliplr(k_minus)

More Answers (2)

Mischa Kim
Mischa Kim on 25 Feb 2014
Edited: Mischa Kim on 25 Feb 2014
Use
k_minus_rev = k_minus(:, [length(k_minus(1,:)):-1:1])
  4 Comments
Jos (10584)
Jos (10584) on 25 Feb 2014
You do not need the length statement by using the keyword END:
MyMatrix_withReversedColumns = MyMatrix(:,end:-1:1)
but I do suggest you stick to FLIPLR. It is the same, but much easier to read!
kk
kk on 2 Apr 2019
Thank you for this answer! It has helped me "merge" two matrices, i.e. creating a matrix consisting of the first column of matrix A, first column of matrix B, second column of matrix A, second column of matrix B, etc.

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rishabh gupta
rishabh gupta on 12 Jan 2018
you can also use: k_minus_rev = k_minus(:, [length(k_minus):-1:1])
  2 Comments
Stephen23
Stephen23 on 12 Jan 2018
Edited: Stephen23 on 12 Jan 2018
The square brackets are totally superfluous, and using end is simpler than using length (of course length should be avoided generally because its output changes depending on the input array size: better to use numel or size with a specific dimension).
So a better (simpler, clearer, less buggy) is exactly as Jos already gave four years ago:
k_minus(:,end:-1:1)
Helen Joan
Helen Joan on 30 Apr 2019
is it possible to do this with a loop?

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