[R] How do I extract Random Forest Terms and Probabilities?

[Liaw, Andy]

#2 can be done simply with predict(fmi, type="prob").  See the help page for predict.randomForest().

Best,
Andy


-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of arun
Sent: Tuesday, November 26, 2013 6:57 PM
To: R help
Subject: Re: [R] How do I extract Random Forest Terms and Probabilities?



Hi,
For the first part, you could do:

fmi2 <- fmi 
attributes(fmi2$terms) <- NULL
capture.output(fmi2$terms)
#[1] "Species ~ Sepal.Length + Sepal.Width + Petal.Length + Petal.Width"

A.k.

On Tuesday, November 26, 2013 3:55 PM, "Lopez, Dan" <lopez235 at llnl.gov> wrote:
Hi R Experts,

I need your help with two question regarding randomForest.


1.       When I run a Random Forest model how do I extract the formula I used so that I can store it in a character vector in a dataframe?
For example the dataframe might look like this if I am running models using the IRIS dataset
#ModelID,Type,

#001,RF,Species ~ Sepal.Length + Sepal.Width + Petal.Length + Petal.Width

fmi<-randomForest(Species~.,iris,mtry=3,ntry=500)
#I know one place where the information is in fmi$terms but not sure how to extract just the formula info. Or perhaps there is somewhere else in fmi that I could get this?


2.       How do I get the probabilities (probability-like values) from the model that was run? I know for the test set I can use predict. And I know to extract the classifications from the model I use fmi$predicted. But where are the probabilities?


Dan
Workforce Analyst
HRIM - Workforce Analytics & Metrics
LLNL


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