[R] duplicate rows in a matrix

[Bill.Venables at csiro.au]

... but you may not want the rows re-ordered.  Here is a possible
modification that uses a similar idea:

m <- matrix(1:(2*nrow(A)), ncol = 2, byrow = TRUE)
AA <- rbind(A, A)[order(m), ]

Bill Venables
 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org]
On Behalf Of Juan Manuel Barreneche
Sent: Saturday, 3 November 2007 2:34 AM
To: Silvia Lipski; r-help list
Subject: Re: [R] duplicate rows in a matrix

My sugestion (for an alphabetically ordered output)

AA <- rbind(A,A)
AA <- AA[order(AA[,1]), ] ## so your matrix gets alphabetically ordered

JM


On Fri, 2007-11-02 at 09:04 -0700, Silvia Lipski wrote:
> Hi!
> 
> Is there a fast way to duplicate rows in a matrix?
> I would like to do the following:
> 
> change a matrix A like:
>      [,1] [,2] 
>  [1,] Kevin 1
>  [2,] Alf 2
> 
> into :
>      [,1] [,2] 
>  [1,] Kevin 1
>  [2,] Kevin 1
>  [3,] Alf 2
>  [4,] Alf 2
> 
> i.e. double all rows. The only way I could think off
> was: rbind(A[1,],A[1,],A[2,],A[2,]) - which is really
> impractible, of course.
> 
> Can anyone help, please?
> Thank you,
> Silvia
> 
> ______________________________________________
> R-help at r-project.org 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.

______________________________________________
R-help at r-project.org 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.