try this: # create data
x.by <http://x.by> <- data.frame(crit1=rep(c(1,2),c(10,10)), crit2=sample(letters[1:4],20,T), val=runif(20)) levels(x.by$crit2) <- c(levels(x.by$crit2), 'small') # add 'small' to the levels y <- by(x.by <http://x.by>, x.by$crit1, function(.grp){ .small <- order(.grp$val) # find the smallest values .grp$crit2[.small[1:min(2,length(.small))]] <- 'small' # make sure we don't exceed vector .grp }) do.call('rbind', y) # put it back together On 11/14/05, Gesmann, Markus <[EMAIL PROTECTED]> wrote: > > Dear R-users, > > I am looking for an elegant way to change some levels of a factor column > in data frame according to a condition. > Lets look at the following data frame: > > > data.frame(crit1=gl(2,5), crit2=factor(letters[1:10]), x=rnorm(10)) > crit1 crit2 x > 1 1 a -1.06957692 > 2 1 b 0.24368402 > 3 1 c -0.24958322 > 4 1 d -1.37577955 > 5 1 e -0.01713288 > 6 2 f -1.25203573 > 7 2 g -1.94348533 > 8 2 h -0.16041719 > 9 2 i -1.91572616 > 10 2 j -0.20256478 > > Now I would like to find for each level in crit1 the two smallest values > of x and change the levels of crit2 to "small", so the result would look > like this: > > crit1 crit2 x > 1 1 small -1.06957692 > 2 1 b 0.24368402 > 3 1 c -0.24958322 > 4 1 small -1.37577955 > 5 1 e -0.01713288 > 6 2 f -1.25203573 > 7 2 small -1.94348533 > 8 2 h -0.16041719 > 9 2 small -1.91572616 > 10 2 j -0.20256478 > > Thank you for advice! > > Markus Gesmann > > ************LNSCNTMCS01*************************************************** > The information in this E-Mail and in any attachments is CON...{{dropped}} > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > -- Jim Holtman Cincinnati, OH +1 513 247 0281 What the problem you are trying to solve? [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
