Hi all, I am running R1.5.0 under unix. I recently used the function 'predict.tree' to make predictions with a tree object and a dataframe of numeric items. The predict.tree internally, calls a function 'delete.response'. When I removed this function call from the source code of predict.tree, it ran 10 times faster without any differences in the result obtained. The documentation for delete.response says that this function is used for deleting the response variable from the dataset. However the documentation for the predict.tree function says that the response variable is ignored during prediction. Could someone tell me why the function 'predict.tree' calls 'delete.response'? Thanks in advance, -Saket. -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On Fri, 23 Aug 2002, Saket Joshi wrote:> Hi all, > > I am running R1.5.0 under unix. > > I recently used the function 'predict.tree' to make predictions with a > tree object and a dataframe of numeric items. The predict.tree internally, > calls a function 'delete.response'. > > When I removed this function call from the source code of predict.tree, it > ran 10 times faster without any differences in the result obtained. > The documentation for delete.response says that this function is used for > deleting the response variable from the dataset. However the documentation > for the predict.tree function says that the response variable is ignored > during prediction. > > Could someone tell me why the function 'predict.tree' calls > 'delete.response'?In order to ignore the response. If you remove the call to delete.response() you will not be able to predict on a new data set that does not have the response variable defined. Eg, following example(predict.tree) data(shuttle, package="MASS") shuttle.tr <- tree(use ~ ., shuttle, subset=1:253, mindev=1e-6, minsize=2) shuttle.tr shuttle1 <- shuttle[254:256, ] # 3 missing cases predict(shuttle.tr, shuttle1) shuttle2<-shutlle1[,-7] #drop response variable ## this doesn't work in your version predict(shuttle.tr, shuttle2) It's very surprising that delete.response is that slow. I haven't seen it take more than a few hundredths of a second -thomas -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._
On Fri, 23 Aug 2002, Saket Joshi wrote:> Hi all, > > I am running R1.5.0 under unix. > > I recently used the function 'predict.tree' to make predictions with a > tree object and a dataframe of numeric items. The predict.tree internally, > calls a function 'delete.response'. > > When I removed this function call from the source code of predict.tree, it > ran 10 times faster without any differences in the result obtained. > The documentation for delete.response says that this function is used for > deleting the response variable from the dataset. However the documentation > for the predict.tree function says that the response variable is ignored > during prediction. > > Could someone tell me why the function 'predict.tree' calls > 'delete.response'?To make prediction possible without having the response variable in `newdata'. Your description of `delete.response' is incorrect: see its help page. -- Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272860 (secr) Oxford OX1 3TG, UK Fax: +44 1865 272595 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- 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 _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._