[R] repeating rows or columns within a matrix

[Uwe Ligges]

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

An interesting exercise! I don't know if it is the smartest way, but the
following line should do the trick for a matrix m:

 matrix(apply(m, 1, function(x) rep(x, 2)), , 4, byrow=TRUE)

Uwe Ligges
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