## A Question about Random Forests

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**1**of**1**### A Question about Random Forests

Hello,

Breiman's Random Forest implementation gives access to various parameters that can be modified - Number of Trees(N), Number of Randomly selected Variables for tree-building (parameter f) , and attributes to build a forest (m), being the most important ones.

For the Orange implementation - The number of trees can be set trivially.

It was not apparent how the other parameters can be tweaked.

How can these parameters be accessed ?

Also - does the Orange implementation have ways of computing the importance of the features (this procedure is found in Breimans implementation ).

If not - are there any recommendations for the changes as above ?

Thanks !

Suraj

Breiman's Random Forest implementation gives access to various parameters that can be modified - Number of Trees(N), Number of Randomly selected Variables for tree-building (parameter f) , and attributes to build a forest (m), being the most important ones.

For the Orange implementation - The number of trees can be set trivially.

It was not apparent how the other parameters can be tweaked.

How can these parameters be accessed ?

Also - does the Orange implementation have ways of computing the importance of the features (this procedure is found in Breimans implementation ).

If not - are there any recommendations for the changes as above ?

Thanks !

Suraj

I lately use Random Forests often, they indeed prove most predictive on many of data sets from bioinformatics (compared with, for instance, C4.5, variants of SVM, and Naive Bayes). I most often limit the depth of the trees that are included. You can do this by setting the properties of the learner (that is, the property of classification tree inducer) by, for example:

- Code: Select all
`forest = orngEnsemble.RandomForestLearner(trees=100, name="forest")`

forest.learner.maxDepth=5

The above would build random forest with the trees with the maximum depth of 5 (root node having a depth of 1, I believe).

Feature importance with rand forests - we have a prototype code for this, you've just reminded me to include it in CVS (should be done in a few days, will post a note here).

Marko

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