## swap columns of a matrix

### Rasmus (view profile)

on 25 Feb 2014
Latest activity Commented on by Helen Joan

### Helen Joan (view profile)

on 30 Apr 2019
Accepted Answer by Thomas

### Thomas (view profile)

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?

on 25 Feb 2014
Edited by Thomas

### Thomas (view profile)

on 25 Feb 2014

You could also use
out= fliplr(k_minus)

Rasmus

### Rasmus (view profile)

on 25 Feb 2014
That is actually easier! :)

### Mischa Kim (view profile)

Answer by Mischa Kim

### Mischa Kim (view profile)

on 25 Feb 2014
Edited by Mischa Kim

### Mischa Kim (view profile)

on 25 Feb 2014

Use
k_minus_rev = k_minus(:, [length(k_minus(1,:)):-1:1])

Show 1 older comment
Mischa Kim

### Mischa Kim (view profile)

on 25 Feb 2014
Basically, when you do
k_minus(:,1)
you extract the sub-matrix consisting of all rows in the first column. With
k_minus(:,[2,1])
you extract all rows of the second, and the first columns, in that order. You can now generalize the last bit
[length(k_minus(1,:)):-1:1]
to extract all columns ( length(k_minus(1,:)) ), placing the last column first, and the first column last, in descending order ( -1 ).
Jos (10584)

### Jos (10584) (view profile)

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 (view profile)

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.

### rishabh gupta (view profile)

Answer by rishabh gupta

### rishabh gupta (view profile)

on 12 Jan 2018

you can also use: k_minus_rev = k_minus(:, [length(k_minus):-1:1])

Stephen Cobeldick

### Stephen Cobeldick (view profile)

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 (view profile)

on 30 Apr 2019
is it possible to do this with a loop?