Extract Node List from XGBoost Model

Extracts node-level attributes from an xgboost model via xgb.model.dt.tree(). Node IDs are globally unique strings in "Tree-Node" format and match the from/to columns produced by edgelist.xgb.Booster.

Usage

# S3 method for class 'xgb.Booster'
nodelist(input_object, treenum = NULL, ...)

Arguments

input_object

An xgboost model object (xgb.Booster)

treenum

Integer vector of 1-based tree numbers to extract (default: NULL extracts all trees).

...

Additional arguments (currently unused)

Value

A data.frame with one row per node and the following columns:

name

Node ID string ("Tree-Node" format, matches edgelist from/to)

is_leaf

Logical: TRUE for leaf nodes

feature

Split variable name (NA for leaves)

split

Split threshold (NA for leaves)

quality

Information gain for splits, leaf score for leaves

cover

Cover (sum of second-order gradient)

missing

Node ID ("Tree-Node" format) where observations with missing values are routed; NA for leaves

treenum

1-based tree number

label

Display label: "<feature>\n< <threshold>" for splits, rounded leaf score for leaves

Examples

if (requireNamespace("xgboost", quietly = TRUE)) {
  data(agaricus.train, package = "xgboost")
  bst <- xgboost::xgboost(
    x = agaricus.train$data,
    y = factor(agaricus.train$label),
    max_depth = 2, nrounds = 2, nthreads = 1
  )
  nl <- nodelist(bst)
  head(nl)
}
#>   name is_leaf                 feature   split      quality      cover missing
#> 1  0-0   FALSE               odor=none 2.00001 4005.7177700 1626.16614     0-2
#> 2  0-1   FALSE spore-print-color=green 2.00001  198.1621090  702.84930     0-4
#> 3  0-2   FALSE         stalk-root=club 2.00001 1159.8702400  923.31677     0-6
#> 4  0-3    TRUE                    <NA>      NA    0.5785417   13.23304    <NA>
#> 5  0-4    TRUE                    <NA>      NA   -0.5614965  689.61627    <NA>
#> 6  0-5    TRUE                    <NA>      NA   -0.4894775  112.35602    <NA>
#>   treenum                        label
#> 1       1               odor=none\n< 2
#> 2       1 spore-print-color=green\n< 2
#> 3       1         stalk-root=club\n< 2
#> 4       1                       0.5785
#> 5       1                      -0.5615
#> 6       1                      -0.4895