# Random Forest: Class specific feature importance

I'm using the bigrf R-package to analyse a dataset with ca. 50.000 observations x 120 variables, classified into two groups.

After growing a forest of 1000 trees, I investigate the importance and relationship of the 120 features in the relation to the 2 classes using, respectively, the fastimp and interactions functions, which produce very nice results.

However, I'm now interested in investigating the problem using 3 (or more) rather than 2 classes. In this case, the Gini variable importance calculated by fastimp only relates to overall importance.

My question is: Is there a way to calculate a class-specific Gini variable importance, or some similar measure?

• see this related thread on SO. Please let me know if you find the solution. – Antoine Aug 15 '15 at 18:07