gbm (version 1.0)

pretty.gbm.tree: Print gbm tree components

Description

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.

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
• SplitVar
  index of which variable is used to split. -1 indicates a terminal node.
• SplitCodePred
  if 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.
• LeftNode
  the index of the row corresponding to the left node.
• RightNode
  the index of the row corresponding to the right node.
• ErrorReduction
  the reduction in the loss function as a result of splitting this node.
• Weight
  the total weight of observations in the node. If weights are all equal to 1 then this is the number of observations in the node.

See Also

gbm, gbm.object