> -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-bounces@r- > project.org] On Behalf Of Schreiber, Stefan > Sent: Tuesday, November 01, 2011 2:29 PM > To: r-help@r-project.org > Subject: [R] factor level issue after subsetting > > Dear list, > > I cannot figure out why, after sub-setting my data, that particular > item > which I don't want to plot is still in the newly created subset (please > see example below). R somehow remembers what was in the original data > set.
That is the nature of factors. Once created, unused levels must be xplicitly dropped plot(droplevels(dat.sub$treat),dat.sub$yield) Hope this is helpful, Dan Daniel J. Nordlund Washington State Department of Social and Health Services Planning, Performance, and Accountability Research and Data Analysis Division Olympia, WA 98504-5204 A work around is exporting and importing the new subset. Then it's > all fine; but I don't like this idea and was wondering what am I > missing > here? > > Thanks! > Stefan > > P.S. I am using R 2.13.2 for Mac. > > > dat<-read.csv("~/MyFiles/data.csv") > > class(dat$treat) > [1] "factor" > > dat > treat yield > 1 cont 98.7 > 2 cont 97.2 > 3 cont 96.1 > 4 cont 98.1 > 5 10 103.0 > 6 10 101.3 > 7 10 102.1 > 8 10 101.9 > 9 30 121.1 > 10 30 123.1 > 11 30 119.7 > 12 30 118.9 > 13 60 109.9 > 14 60 110.1 > 15 60 113.1 > 16 60 112.3 > > plot(dat$treat,dat$yield) > > dat.sub<-dat[which(dat$treat!='cont')] > > class(dat.sub$treat) > [1] "factor" > > dat.sub > treat yield > 5 10 103.0 > 6 10 101.3 > 7 10 102.1 > 8 10 101.9 > 9 30 121.1 > 10 30 123.1 > 11 30 119.7 > 12 30 118.9 > 13 60 109.9 > 14 60 110.1 > 15 60 113.1 > 16 60 112.3 > > plot(dat.sub$treat,dat.sub$yield) > > [[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. ______________________________________________ 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.