From: Eleni Rapsomaniki > > Hi Andy, > > > > I'm using R (windows) version 2.1.1, randomForest version 4.15. > > ^^^^^^^^^^^^^^^^^^^^^^^^^ > > Never seen such a version... > Ooops! I meant 4.5-15 > > > > I then save each tree to a file so I can combine them all > > > afterwards. There are no memory issues when > > > keep.forest=FALSE. But I think that's the bit I need for > > > future predictions (right?). > > > > Yes, but what is your question? (Do you mean each *forest*, > > instead of each *tree*?) > I mean the component of the object that is created from > randomForest that has > the name "forest" (and takes up all the memory!).
Yes, the forest can take up quite a bit of space. You might consider setting nodesize larger and see if that gives you sufficient space saving w/o compromising prediction performance. > > > A bit off the subject, but should the order at which at rows > > > (ie. sets of explanatory variables) are passed to the > > > randomForest function affect the result? I have noticed that > > > if I pick a random unordered sample from my control data for > > > training the error rate is much lower than if I a take an > > > ordered sample. This remains true for all my cross-validation > > > results. > > > > I'm not sure I understand. In randomForest() (as in other > > functions) variables are in columns, rather than rows, so > > are you talking about variables (columns) in different order > > or data (rows) in different order? > > Yes, sorry I confused you. I mean the order at which data > (rows) is passed, not > columns. Then I'm not sure what you mean by difference in performance, even in cross-validation. Perhaps you can show some example? Each tree in the forest is grown on a random sample from the data, so the order of the row can not matter. > Finally, I see from > http://www.stat.berkeley.edu/~breiman/RandomForests/cc_home.htm#inter > > that there is a component in Breiman's implementation of > randomForest that > computes interactions between parameters. Has this been > implemented in R yet? No. Prof. Breiman told me that is very experimental, and he wouldn't mind if that doesn't make it into the R package. Since I have other priorities for the package, that naturally went to the backburner. Cheers, Andy > Many thanks for your time and help. > Eleni Rapsomaniki > > > ---------------------------------------------------------------- > This message was sent using IMP, the Internet Messaging Program. > > ______________________________________________ [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.
