[R] listing a sequence of vectors in a matrix
Robin Hankin
r.hankin at noc.soton.ac.uk
Tue Aug 22 14:58:47 CEST 2006
Hi
> f <- function(a,n){(1:a)[1:n]}
> t(sapply(c(2,3,4,4,4,5,6),f,n=5))
[,1] [,2] [,3] [,4] [,5]
[1,] 1 2 NA NA NA
[2,] 1 2 3 NA NA
[3,] 1 2 3 4 NA
[4,] 1 2 3 4 NA
[5,] 1 2 3 4 NA
[6,] 1 2 3 4 5
[7,] 1 2 3 4 5
>
>
HTH
rksh
On 22 Aug 2006, at 12:29, Sara-Jane Dunn wrote:
> Hi,
>
> I'm having trouble applying the matrix function. I'd like to be
> able to
> create a matrix of vectors filled in by rows, which are not all the
> same
> length, and so I need it to fill in NAs where applicable.
>
> It's easiest to explain with a simple example:
>
> Suppose vec = c(3,4,5). How can I form a matrix of the vectors 1:vec
> [j]
> for j=1:3?
> i.e. 1 2 3 NA NA
> 1 2 3 4 NA
> 1 2 3 4 5
> I've tried matrix(c(1:vec[j]),nrow=max(j),ncol=max(vec)) but it will
> only give me a matrix with repeated values for j=1, like 1 2 3 1
> 2
> 3 1 2 3 1
> 2 3 1 2 3
>
> Also using the list function hasn't got me anywhere either..
>
> Any help/ideas would be greatly appreciated!
>
> Many thanks,
> Sara-Jane Dunn
>
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