What is the output of random forest?
For classification tasks, the output of the random forest is the class selected by most trees. For regression tasks, the mean or average prediction of the individual trees is returned. Random decision forests correct for decision trees’ habit of overfitting to their training set.
What does MeanDecreaseGini mean?
-MeanDecreaseGini. Gini is defined as “inequity” when used in describing a society’s distribution of income, or a measure of “node impurity” in tree-based classification.
What is mean decrease in impurity?
It is sometimes called “gini importance” or “mean decrease impurity” and is defined as the total decrease in node impurity (weighted by the probability of reaching that node (which is approximated by the proportion of samples reaching that node)) averaged over all trees of the ensemble.
How to interpret the output of a random forest?
In addition to the great answers above, I found interesting another instrument designed to explore the general outputs of a random forest: function explain_forest the package randomForestExplainer. See here for further details. Please, note: localImp has to be set as TRUE, otherwise the explain_forest will quit with an error
How is random forest used in classification and regression?
Classification and Regression with Random Forest. randomForest implements Breiman’s random forest algorithm (based on Breiman and Cutler’s original Fortran code) for classification and regression. It can also be used in unsupervised mode for assessing proximities among data points.
What happens if randomForest is set to false?
If set to TRUE, give a more verbose output as randomForest is run. If set to some integer, then running output is printed for every do.trace trees. If set to FALSE, the forest will not be retained in the output object. If xtest is given, defaults to FALSE. perform bias correction for regression? Note: Experimental. Use at your own risk.
What are the optional parameters for the randomForest function?
Use at your own risk. Should an n by ntree matrix be returned that keeps track of which samples are “in-bag” in which trees (but not how many times, if sampling with replacement) optional parameters to be passed to the low level function randomForest.default.