Thanks a lot Andy, Do I need to have centering and scaling before sending data into rpart and randomForest?
I knew for LDA and QDA, it does not matter... And for ridge, it matters; Thanks a lot! Michael. On 3/8/06, Liaw, Andy <[EMAIL PROTECTED]> wrote: > > The algorithm has something slicker than cross-validation. That's the > whole OOB business mentioned in the R News article. The number of trees > isn't really a parameter, as it doesn't hurt to have `too many trees' (other > than wasting computing resources). Some people routinely run more than > 10,000 trees just to make sure. > > Some times mtry does matter (though that's more of an exception than the > rule). I can find pathological cases where mtry=1 is the best, or > mtry=number of covariates (bagging) is best, but when given a real data, one > almost never have any idea. > > Andy > > -----Original Message----- > *From:* Michael [mailto:[EMAIL PROTECTED] > *Sent:* Wednesday, March 08, 2006 8:22 PM > *To:* Liaw, Andy > *Cc:* [email protected] > *Subject:* Re: [R] how to use the randomForest and rpart function? > > Hi Andy, > > Does the randomForest have a Cross Validation built-in to decide what is > the best number of trees or I have to find the best number manually by > myself? > > Thanks a lot! > > Michael. > > On 3/7/06, Liaw, Andy <[EMAIL PROTECTED]> wrote: > > > > Yes, I do know. That's why I pointed you to the reference linked from > > the help page. > > > > BTW, there's also an R News article describing the initial version of > > the package. Have you perused that? > > > > Andy > > > > -----Original Message----- > > *From:* Michael [mailto:[EMAIL PROTECTED] > > *Sent:* Tuesday, March 07, 2006 9:27 PM > > *To:* Liaw, Andy > > *Cc:* [email protected] > > *Subject:* Re: [R] how to use the randomForest and rpart function? > > > > It did not have a legend showing on which color is for class1, which > > color is for class2, etc... > > > > I've read the R-help page. > > > > It lists a lot of options, but it did not say which ones are the key > > parameters that people use most for improving performance... > > > > Do you know? > > > > On 3/7/06, Liaw, Andy <[EMAIL PROTECTED]> wrote: > > > > > > As ?plot.randomForest says, it plots error rates. In addition to > > > overall > > > error rates, it also plots error rates for each class. > > > > > > As to the options in randomForest, read about the options in the help > > > page > > > and the reference linked from the help page. > > > > > > Andy > > > > > > From: Michael > > > > > > > > When I plot the randomForest object, it shows a graph with 3 > > > > lines, green, red and black, what's the meaning of these three > > > lines? > > > > > > > > On 3/7/06, Michael < [EMAIL PROTECTED]> wrote: > > > > > > > > > > Hi all, > > > > > > > > > > I am trying to play around with the randomForest function for > > > > > classification. I know its performance is great. > > > > > > > > > > I am currently using the default options. > > > > > > > > > > It has many options. > > > > > > > > > > How do I further tweak the options so that I can make its > > > > performance > > > > > even better? > > > > > > > > > > What are the options that are mostly used? > > > > > > > > > > Thanks a lot! > > > > > > > > > > M > > > > > > > > > > > > > [[alternative HTML version deleted]] > > > > > > > > ______________________________________________ > > > > [email protected] mailing list > > > > https://stat.ethz.ch/mailman/listinfo/r-help > > > > PLEASE do read the posting guide! > > > > http://www.R-project.org/posting-guide.html > > > <http://www.r-project.org/posting-guide.html> > > > > > > > > > > > > > > > > > ------------------------------------------------------------------------------ > > > > > > Notice: This e-mail message, together with any attachments, contains > > > information of Merck & Co., Inc. 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