Thanks Gavin and sorry to all for this unnecessary question. B.
Gavin Simpson wrote: > > On Tue, 2008-09-16 at 10:47 -0700, Birgitle wrote: >> Hello R-User! >> >> I try to do the following: >> >> New<-iris[c(1:7,90:97),1:5] >> New.rpart<-rpart(Species~., data=New, method="class") >> >> New.rpart >> n= 15 >> >> node), split, n, loss, yval, (yprob) >> * denotes terminal node >> >> 1) root 15 7 versicolor (0.4666667 0.5333333) * >> >> Does it mean it is not possible to find a variable that splits my groups >> or >> are my groups just to small? >> Is there a way to find out the variable that splits my groups best? > > Yes, as always, read the help file ;-) > > ?rpart leads you to ?rpart.control, which has argument minsplit with > default 20, which is the minimum number of observations in a node for a > split to be attempted. As 15 is less than 20, the root node could not be > split. > > E.g.: >> New<-iris[c(1:7,90:97),1:5] >> New.rpart<-rpart(Species~., data=New, method="class", control = > rpart.control(minsplit = 2)) >> New.rpart > n= 15 > > node), split, n, loss, yval, (yprob) > * denotes terminal node > > 1) root 15 7 versicolor (0.4666667 0.5333333) > 2) Petal.Length< 2.5 7 0 setosa (1.0000000 0.0000000) * > 3) Petal.Length>=2.5 8 0 versicolor (0.0000000 1.0000000) * > > HTH > > G > >> >> Thanks in advance for help. >> >> B. >> >> ----- >> The art of living is more like wrestling than dancing. >> (Marcus Aurelius) > -- > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > Dr. Gavin Simpson [t] +44 (0)20 7679 0522 > ECRC, UCL Geography, [f] +44 (0)20 7679 0565 > Pearson Building, [e] gavin.simpsonATNOSPAMucl.ac.uk > Gower Street, London [w] http://www.ucl.ac.uk/~ucfagls/ > UK. WC1E 6BT. [w] http://www.freshwaters.org.uk > %~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~%~% > > ______________________________________________ > 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. > > ----- The art of living is more like wrestling than dancing. (Marcus Aurelius) -- View this message in context: http://www.nabble.com/rpart-with-only-two-small-groups-tp19516515p19526594.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
