Hi:
Here are a couple of ways using the doBy and plyr packages:
library(doBy)
library(plyr)
# doBy:
subsetBy(~ wool + tension, subset = breaks == max(breaks), data =
warpbreaks)
breaks wool tension
A|H 43 A H
A|L 70 A L
A|M 36 A M
B|H 28 B H
B|L 44 B L
B|M 42 B M
# plyr
ddply(warpbreaks, .(wool, tension), subset, breaks == max(breaks))
breaks wool tension
1 70 A L
2 36 A M
3 43 A H
4 44 B L
5 42 B M
6 28 B H
HTH,
Dennis
On Tue, May 18, 2010 at 1:58 AM, Tim Van den Bulcke <
vandenbulcke...@gmail.com> wrote:
> Hi,
>
>
> I'd like to select one row in a data frame per subset which is maximal for
> a
> particular value. I'm pretty close to the solution in the sense that I can
> easily select the maximal values per subset using "aggregate", but I can't
> really figure out how to select the rows in the original data frame that
> are
> associated with these maximal values.
>
>
> library(stats)
> # this returns the list with maximal values for breaks per wool/tension
> subset
> maxValues = aggregate(warpbreaks$breaks, list(wool = wool, tension =
> tension), max)
>
> # now i'd like the subset of the rows in warpbreaks that are associated
> with
> these maximal values
>
>
>
> Thank you in advance!
>
> Tim.
>
> [[alternative HTML version deleted]]
>
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