Extract Edgelist from XGBoost Model

Converts an xgboost model object into a network edgelist representation using xgb.model.dt.tree(). Each edge connects a split node to one of its two children (yes/no branches). Node IDs are globally unique strings in "Tree-Node" format (e.g., "0-3").

Usage

# S3 method for class 'xgb.Booster'
edgelist(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 the following columns:

from

Parent node ID string ("Tree-Node" format)

to

Child node ID string

feature

Name of the split variable (or 0-based index string when feature names are absent)

split

Numeric split threshold

quality

Information gain at the split

cover

Number of observations covered

treenum

1-based tree number

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
  )
  el <- edgelist(bst)
  head(el)
}
#>   from  to                 feature   split   quality     cover treenum
#> 1  0-0 0-1               odor=none 2.00001 4005.7178 1626.1661       1
#> 2  0-1 0-3 spore-print-color=green 2.00001  198.1621  702.8493       1
#> 3  0-2 0-5         stalk-root=club 2.00001 1159.8702  923.3168       1
#> 4  1-0 1-1               odor=none 2.00001 2170.2515 1511.9938       2
#> 5  1-1 1-3 spore-print-color=green 2.00001  112.4270  638.1204       2
#> 6  1-2 1-5        bruises?=bruises 2.00001  826.5358  873.8734       2