[R] split-apply question

[hadley wickham]

On Fri, Oct 2, 2009 at 4:24 AM, jim holtman <jholtman at gmail.com> wrote:
> try this:
>
>> x <- read.table(textConnection("x1  x2  x3
> + A   1    1.5
> + B   2    0.9
> + B   3    2.7
> + C   7    1.8
> + D   7    1.3"), header=TRUE)
>> closeAllConnections()
>> do.call(rbind, lapply(split(seq(nrow(x)), x$x1), function(.row){
> +     x[.row[which.min(x$x2[.row])],]
> + }))
>  x1 x2  x3
> A  A  1 1.5
> B  B  2 0.9
> C  C  7 1.8
> D  D  7 1.3
>>

Or, using plyr and subset

library(plyr)
ddply(x, "x1", subset, x2 == min(x2))

Hadley

-- 
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