I've been using the package rpart with R 1.3.0 for Windows to produce simple classification trees for some measurement data from paleontological specimens. Both the rpart documentation and the output confirm that the program produces splits on continuous data that leave "holes" in the data. It is probably of little practical importance, but is there a reason why the binary splits are constructed in the form (e.g): x7 < 37 x7 > 37 as opposed to the actual CART (tm) methodology of: x7 <= 37 x7 > 37 It seems to me that if one were to use rpart to classify an unknown case where x7 = 37, the program wouldn't actually know which way to move the case. I've read through the rpart technical report, the rpart user's manual, the rpart help file and see this practice illustrated, but don't find any explanation for this minor (and probably trivial) departure from the methodology illustrated in the CART program and in the Breiman et al book. ===================== Dr. Marc R. Feldesman Professor and Chairman Anthropology Department Portland State University 1721 SW Broadway Portland, Oregon 97201 email: feldesmanm at pdx.edu phone: 503-725-3081 fax: 503-725-3905 http://web.pdx.edu/~h1mf PGP Key Available On Request ====================== "Anyway, no drug, not even alcohol, causes the fundamental ills of society. If we're looking for the source of our troubles, we shouldn't test people for drugs, we should test them for stupidity, ignorance, greed and love of power." P.J. O'Rourke Powered by Optiplochoerus and Windows 2000 (scary isn't it?) -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
rpart puzzle
1 message · Marc Feldesman