plot: Plot of VSURF results

Description

This function plots 4 graphs illustrating VSURF results.

Usage

## S3 method for class 'VSURF':
plot(x, ...)

Arguments

An object of class VSURF, which is the result of the VSURF function.

...

Details

The 2 graphs of the top row correspond to the "thresholding step". The top left graph plots the mean variable importance in decreasing order (black curve). The red horizontal line represent the value of the threshold. The top right graph plots the standard deviation of variable importance with variables ordered according to their mean variable importance in decreasing order (black curve). The green line represents the predictions given by a CART tree fitted to the black curve (the standard deviations). Finally, the dotted horizontal red line represents the minimum value of the CART predictions, which actually is the value of the threshold. The bottom left graph corresponds to the "interpretation step". It plots the mean OOB error rate of embedded random forests models (from the one with only one variable as predictor, to the one with all variables kept after the "thresholding step"). The vertical red line indicates the retained model. The bottom right graph corresponds to the "predicton step". It plots the mean OOB error rate of embedded random forests models (the difference, here, being that variables are added to the model in a step-wise manner). The retained model is the final one.

References

Genuer, R. and Poggi, J.M. and Tuleau-Malot, C. (2010), Variable selection using random forests, Pattern Recognition Letters 31(14), 2225-2236

Examples

Run this code

data(iris)
iris.vsurf <- VSURF(x=iris[,1:4], y=iris[,5], ntree=100, nfor.thres=20,
                    nfor.interp=10, nfor.pred=10)
plot(iris.vsurf)

# A more interesting example with toys data (see ?toys)
# (less than 1 min to execute)
data(toys)
toys.vsurf <- VSURF(x=toys$x, y=toys$y)
plot(toys.vsurf)