# [R] repeating rows or columns within a matrix

Laurent Gautier laurent at genome.cbs.dtu.dk
Thu Mar 21 14:21:10 CET 2002

```On Thu, Mar 21, 2002 at 12:19:37PM +0200, Juhana Vartiainen wrote:
> Hello
>
> Spse I have a matrix, say
>
> 1 2 3
> 4 5 6
> 7 8 9
>
> and I would like to expand it by repeating rows within the matrix, to
> get, if the repeating factor is 2, say:
>
> 123
> 123
> 456
> 456
> 789
> 789
>
> (or columnwise as well) . There must be a smart way of doing that?
>
> Many thanks
>
> Juhana Vartiainen
> juhana.vartiainen at labour.fi
>
>
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I do not know if it is a smart way, but that's a way:

m <- matrix(1:9, 3, 3, byrow=T)
rep.fact <- 2  # repeating factor, say 2
mm <- matrix(rep(m, rep(rep.fact, length(m))), nrow(m)*rep.fact, ncol(m))

Hopin' it helps,

Laurent

--
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Laurent Gautier			CBS, Building 208, DTU
PhD. Student			D-2800 Lyngby,Denmark
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```

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