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> mat <- matrix(1:16,4,4)> mat [,1] [,2] [,3] [,4] [1,] 1 5 9 13 [2,] 2 6 10 14 [3,] 3 7 11 15 [4,] 4 8 12 16 > apply(mat,2,rev) [,1] [,2] [,3] [,4] [1,] 4 8 12 16 [2,] 3 7 11 15 [3,] 2 6 10 14 [4,] 1 5 9 13 ------------------------------------------------------------------- Jacques VESLOT CNRS UMR 8090 I.B.L (2?me ?tage) 1 rue du Professeur Calmette B.P. 245 59019 Lille Cedex Tel : 33 (0)3.20.87.10.44 Fax : 33 (0)3.20.87.10.31 http://www-good.ibl.fr ------------------------------------------------------------------- niederlein-rstat at yahoo.de a ?crit :> Hello, > > I'm an absolut beginner with R and now I got a 2D vector with numbers. I would like to mirror this vector now by the rows (so that the first row becomes last, second becomes one before last, ...). > I don't know if there is any method I can use to do this. > Could you please help me? > > Antje > > > --------------------------------- > Was Sie schon immer wissen wollten aber nie zu Fragen trauten? Yahoo! Clever hilft Ihnen. > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >
Hi Antje
use the fact that n:1 counts backwards from n, and then use this as
a row index:
> m <- matrix(1:30,5,6)
> m[nrow(m):1,]
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] 5 10 15 20 25 30
[2,] 4 9 14 19 24 29
[3,] 3 8 13 18 23 28
[4,] 2 7 12 17 22 27
[5,] 1 6 11 16 21 26
[
a more general answer would be
library(magic)
arev(m,1)
]
HTH
rksh
On 28 Jul 2006, at 08:50, <niederlein-rstat at yahoo.de> wrote:
> Hello,
>
> I'm an absolut beginner with R and now I got a 2D vector with
> numbers. I would like to mirror this vector now by the rows (so
> that the first row becomes last, second becomes one before last, ...).
> I don't know if there is any method I can use to do this.
> Could you please help me?
>
> Antje
>
>
> ---------------------------------
> Was Sie schon immer wissen wollten aber nie zu Fragen trauten?
> Yahoo! Clever hilft Ihnen.
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-
> guide.html
> and provide commented, minimal, self-contained, reproducible code.
--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
tel 023-8059-7743