Hello Andy and other R-help readers, I've just realized that your function *does* answer my needs at full. (That's what happens when reading something late at night I guess...)
Thanks again Andy for your help! Best, Tal ----------------Contact Details:------------------------------------------------------- Contact me: [email protected] | 972-52-7275845 Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) | www.r-statistics.com (English) ---------------------------------------------------------------------------------------------- On Tue, Jan 25, 2011 at 12:33 AM, Tal Galili <[email protected]> wrote: > Hi Andy, > > Thank you for your response. > > I've already came by this function but also noticed that the help file > states that: > "This method does *not* currently provide classspecific measures of > importance when the *response is a factor*." > > Which is the case I need to deal with. > > Any suggestions as to how to adjust this function for the factor-response > case? > > > Best, > Tal > > > > > ----------------Contact > Details:------------------------------------------------------- > Contact me: [email protected] | 972-52-7275845 > Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il (Hebrew) | > www.r-statistics.com (English) > > ---------------------------------------------------------------------------------------------- > > > > > On Mon, Jan 24, 2011 at 5:21 PM, Liaw, Andy <[email protected]> wrote: > >> Check out caret::varImp.rpart(). It's described in the original CART >> book. >> >> Andy >> >> From: Tal Galili >> > >> > Hello all, >> > >> > When building a CART model (specifically classification tree) >> > using rpart, >> > it is sometimes interesting to know what is the importance of >> > the various >> > variables introduced to the model. >> > >> > Thus, my question is: *What common measures exists for >> > ranking/measuring >> > variable importance of participating variables in a CART >> > model? And how can >> > this be computed using R (for example, when using the rpart package)* >> > >> > For example, here is some dummy code, created so you might show your >> > solutions on it. This example is structured so that it is clear that >> > variable x1 and x2 are "important" while (in some sense) x1 is more >> > important then x2 (since x1 should apply to more cases, thus make more >> > influence on the structure of the data, then x2). >> > >> > set.seed(31431) >> > >> > n <- 400 >> > >> > x1 <- rnorm(n) >> > >> > x2 <- rnorm(n) >> > >> > x3 <- rnorm(n) >> > >> > x4 <- rnorm(n) >> > >> > x5 <- rnorm(n) >> > >> > X <- data.frame(x1,x2,x3,x4,x5) >> > >> > y <- sample(letters[1:4], n, T) >> > >> > y <- ifelse(X[,2] < -1 , "b", y) >> > >> > y <- ifelse(X[,1] < 0 , "a", y) >> > >> > require(rpart) >> > >> > fit <- rpart(y~., X) >> > >> > plot(fit); text(fit) >> > >> > info.gain.rpart(fit) # your function - telling us on each variable how >> > important it is >> > >> > (references are always welcomed) >> > >> > >> > Thanks! >> > >> > Tal >> > >> > ----------------Contact >> > Details:------------------------------------------------------- >> > Contact me: [email protected] | 972-52-7275845 >> > Read me: www.talgalili.com (Hebrew) | www.biostatistics.co.il >> > (Hebrew) | >> > www.r-statistics.com (English) >> > -------------------------------------------------------------- >> > -------------------------------- >> > >> > [[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 >> > and provide commented, minimal, self-contained, reproducible code. >> > >> Notice: This e-mail message, together with any attachments, contains >> information of Merck & Co., Inc. (One Merck Drive, Whitehouse Station, >> New Jersey, USA 08889), and/or its affiliates Direct contact information >> for affiliates is available at >> http://www.merck.com/contact/contacts.html) that may be confidential, >> proprietary copyrighted and/or legally privileged. It is intended solely >> for the use of the individual or entity named on this message. If you are >> not the intended recipient, and have received this message in error, >> please notify us immediately by reply e-mail and then delete it from >> your system. >> >> > [[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 and provide commented, minimal, self-contained, reproducible code.
