... On 10 mar, 17:00, "Liaw, Andy" <[EMAIL PROTECTED]> wrote: > Are you sure there are 100 sites in your data? Here's an example: > > R> library(randomForest)randomForest4.5-23 > Type rfNews() to see new features/changes/bug fixes. > R> f <- factor(sample(1:4, nrow(iris), replace=TRUE)) > R> rf1 <-randomForest(iris[1:4], iris[[5]], strata=f,sampsize=rep(5, > nlevels(f))) > R> rf1 > > Call: > randomForest(x = iris[1:4], y = iris[[5]], strata = f,sampsize= > rep(5, nlevels(f))) > Type of random forest: classification > Number of trees: 500 > No. of variables tried at each split: 2 > > OOB estimate of error rate: 4.67% > Confusion matrix: > setosa versicolor virginica class.error > setosa 50 0 0 0.00 > versicolor 0 47 3 0.06 > virginica 0 4 46 0.08 > > > > > -----Original Message----- > > From: [EMAIL PROTECTED] > > [mailto:[EMAIL PROTECTED] On Behalf Of Naiara Pinto > > Sent: Sunday, March 09, 2008 5:19 PM > > To: [EMAIL PROTECTED] > > Subject: [R]sampsizein Random Forests > > > Hi all, > > > I have a dataset where each point is assigned to a class A, B, C, or > > D. Each point is also assigned to a study site. Each study site is > > coded with a number ranging between 1-100. This information is stored > > in the vector studySites. > > > I want to run randomForests using stratified sampling, so I > > chose the option > > strata = factor(studySites) > > > But I am not sure how to control the number of samples taken from each > > study site. I tried to use 10 points from each study site: > > mySampSize = rep(10, 100) > > > So my function call looks like: > > RF =randomForest(myClass~., data=myData, mtry=5, importance=TRUE, > > strata = factor(studySites),sampsize=mySampSize) > > > ButrandomForestgives me the following error: > > Error inrandomForest.default(m, y, ...) : > >sampsizecan not be larger than class frequency > > > Does anybody have any idea why this happens? > > > Thank you very much, > > > Naiara. > > > ______________________________________________ > > [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 attachme...{{dropped:15}} > > ______________________________________________ > [EMAIL PROTECTED] mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guidehttp://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.
______________________________________________ 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.
