[R] repeating rows or columns within a matrix

[Andreas Kiermeier]

>>>>> "Juhana" == Juhana Vartiainen <juhana.vartiainen at labour.fi> writes:

    Juhana> Hello
    Juhana> Spse I have a matrix, say

    Juhana> 1 2 3
    Juhana> 4 5 6
    Juhana> 7 8 9

    Juhana> and I would like to expand it by repeating rows within the matrix, to
    Juhana> get, if the repeating factor is 2, say:

    Juhana> 123
    Juhana> 123
    Juhana> 456
    Juhana> 456
    Juhana> 789
    Juhana> 789

    Juhana> (or columnwise as well) . There must be a smart way of doing that?

Juhana,

you could try the kronecker product

> z <- matrix(1:9,ncol=3,byrow=T)
> z
     [,1] [,2] [,3]
[1,]    1    2    3
[2,]    4    5    6
[3,]    7    8    9
> kronecker(z, c(1,1))
     [,1] [,2] [,3]
[1,]    1    2    3
[2,]    1    2    3
[3,]    4    5    6
[4,]    4    5    6
[5,]    7    8    9
[6,]    7    8    9

Cheers,

Andreas

-- 
Andreas Kiermeier
Senior Biometrician
BiometricsSA (Adelaide University/SARDI)
GPO Box 397, Adelaide, SA 5001, Australia
Email: Andreas.Kiermeier at adelaide.edu.au
WWW: http://www.BiometricsSA.adelaide.edu.au/
Ph:  +61 8 8303 6819
Fax: +61 8 8303 6761

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