Samir Rachid Zaim
2019-Aug-10 18:36 UTC
[R] Question on extracting subsampled features from node in Random forest Package
Hi all, ------------------------------------------------------------------------------------------------------------ *Question:* *Is there a way to see what variables are subsampled in a node in a tree in a random forest?* ------------------------------------------------------------------------------------------------------------ I posted this question on cross-validated *(see here) <https://stats.stackexchange.com/questions/419872/is-there-a-way-to-see-what-variables-are-subsampled-in-a-node-in-a-tree-in-a-ran>*, but they closed it as "off-topic", so I'll rewrite and hopefully get some feedback there. I'd figure I'd also try here. In a random forest, the *mtry* parameter determines what percentage*/*proportion of features gets subsampled at each node in a tree in a *randomForest* classifier. At the moment, if I search through the randomForest object, I can get a tree map that shows you what feature was chosen, and what was the splitting value for that node. My question, is, is there a way to also see what features were subsampled for that node? If not, is than an option for a future release? The example below shows what's currently available when you scan through the forest in the rf.object, but it seems to only include the final variable and splitting value, rather than the entire set of features at each node. ------------------------------------------------------------------------------------------------------------ *Example:* X = matrix(rnorm(1000), ncol=10) beta= rep(1,10) z = X %*% beta y = factor(rbinom(100, size=1, prob= 1/(1 + exp(-z)))) rf.object <- randomForest::randomForest(X,y, keep.forest=T) str(rf.object$forest) ------------------------------------------------------------------------------------------------------------ I appreciate any and all help. Thanks!! -- Samir Rachid Zaim, PhD Student in Statistics and Data Science, Data Science Ambassador, College of Medicine University of Arizona Bioscience Research Lab 1230 N Cherry Ave, Tucson, AZ 85719 email: samirrachidzaim at email.arizona.edu website: https://samirrachidzaim.github.io/ [[alternative HTML version deleted]]