[R] Collapse data matrix with extra info separated by commas

[jim holtman]

try this:

> x <- lapply(split(test, list(test$a, test$b), drop=TRUE), function(.data){
+     data.frame(a=.data$a[1], b=.data$b[1], c=paste(.data$c, collapse=','))
+ })
> do.call(rbind, x)
    a b     c
A.1 A 1   1,2
B.1 B 1 5,6,7
A.2 A 2   3,4
>


On Mon, Apr 6, 2009 at 10:38 AM, Daniel Brewer <daniel.brewer at icr.ac.uk> wrote:
> Hello,
>
> I would like to reshape my data for presentation purposes from something
> like this:
>> test <-
> data.frame(a=c("A","A","A","A","B","B","B"),b=c(1,1,2,2,1,1,1),c=1:7)
>> test
>  a b c
> 1 A 1 1
> 2 A 1 2
> 3 A 2 3
> 4 A 2 4
> 5 B 1 5
> 6 B 1 6
> 7 B 1 7
>
> to something like this:
>  a b c
> 1 A 1 1,2
> 3 A 2 3,4
> 5 B 1 5,6,7
>
> This seems to be the sort of the thing that the reshape library should
> be able to do, but I just can't work out how to do it.
>
> Many thanks
>
> Dan
>
> --
> **************************************************************
> Daniel Brewer, Ph.D.
>
> Institute of Cancer Research
> Molecular Carcinogenesis
> Email: daniel.brewer at icr.ac.uk
> **************************************************************
>
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