try this:
> do.call(rbind, lapply(split(x, x$X1), function(.grp){
+ .ord <- .grp[order(.grp$X2, decreasing = TRUE),]
+ .ord[seq(min(5, nrow(.grp))),]
+ }))
X1 X2
1.10 1 10
1.9 1 9
1.8 1 8
1.7 1 7
1.6 1 6
2.25 2 25
2.24 2 24
2.23 2 23
2.22 2 22
2.21 2 21
On Fri, Dec 10, 2010 at 9:18 AM, andrija djurovic <djandr...@gmail.com> wrote:
> Hi R-help,
>
>
>
> I am trying to find a way to select five highest values in data frame
> according some variable. I will demonstrate:
>
> c
>
> X1 X2
>
> 1 1 1
>
> 2 1 2
>
> 3 1 3
>
> 4 1 4
>
> 5 1 5
>
> 6 1 6
>
> 7 1 7
>
> 8 1 8
>
> 9 1 9
>
> 10 1 10
>
> 11 2 11
>
> 12 2 12
>
> 13 2 13
>
> 14 2 14
>
> 15 2 15
>
> 16 2 16
>
> 17 2 17
>
> 18 2 18
>
> 19 2 19
>
> 20 2 20
>
> 21 2 21
>
> 22 2 22
>
> 23 2 23
>
> 24 2 24
>
> 25 2 25
>
>
>
> So I would like to select a rows with higest values of X2 inside X1.
> Expected result should be:
>
> X1 X2
>
> 1 10
>
> 1 9
>
> 1 8
>
> 1 7
>
> 1 6
>
> 2 25
>
> 2 24
>
> 2 23
>
> 2 22
>
> 2 21
>
>
>
> I first oreded the data frame using
>
> c=c[with(c,order(X1,-X2)),]
>
> but I need a help to select highes five. It is easy to select when I have
> just 2 unique values of X1 but what is if I have 500 unique values in X1?
>
>
>
> Thanks
>
> Andrija
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
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