pretty.gbm.tree

From gbm v0.6
0th

Percentile

Print gbm tree components

gbm stores the collection of trees used to construct the model in a compact matrix structure. This function extracts the information from a single tree and displays it in a slightly more readable form. This function is mostly for debugging purposes and to satisfy some users' curiosity.

Keywords
print
Usage
pretty.gbm.tree(object,
i.tree = 1)
Arguments
object
a gbm.object initially fit using gbm
i.tree
the index of the tree component to extract from object and display
Value

• pretty.gbm.tree returns a data frame. Each row corresponds to a node in the tree. Columns indicate
• SplitVarindex of which variable is used to split. -1 indicates a terminal node.
• SplitCodePredif the split variable is continuous then this component is the split point. If the split variable is categorical then this component contains the index of object\$c.split that describes the categorical split. If the node is a terminal node then this is the prediction.
• LeftNodethe index of the row corresponding to the left node.
• RightNodethe index of the row corresponding to the right node.
• ErrorReductionthe reduction in the loss function as a result of splitting this node.
• Weightthe total weight of observations in the node. If weights are all equal to 1 then this is the number of observations in the node.

gbm, gbm.object