View source: R/xgb.model.dt.tree.R
| xgb.model.dt.tree | R Documentation |
Parse a boosted tree model text dump into a data.table structure.
xgb.model.dt.tree(model, trees = NULL, use_int_id = FALSE, ...)
model |
Object of class If the model contains categorical features, an error will be thrown. |
trees |
An integer vector of (base-1) tree indices that should be used. The default
( |
use_int_id |
A logical flag indicating whether nodes in columns "Yes", "No", and
"Missing" should be represented as integers (when |
... |
Not used. Some arguments that were part of this function in previous XGBoost versions are currently deprecated or have been renamed. If a deprecated or renamed argument is passed, will throw a warning (by default) and use its current equivalent instead. This warning will become an error if using the 'strict mode' option. If some additional argument is passed that is neither a current function argument nor a deprecated or renamed argument, a warning or error will be thrown depending on the 'strict mode' option. Important: |
Note that this function does not work with models that were fitted to
categorical data, and is only applicable to tree-based boosters (not gblinear).
A data.table with detailed information about tree nodes. It has the following columns:
Tree: integer ID of a tree in a model (zero-based index).
Node: integer ID of a node in a tree (zero-based index).
ID: character identifier of a node in a model (only when use_int_id = FALSE).
Feature: for a branch node, a feature ID or name (when available);
for a leaf node, it simply labels it as "Leaf".
Split: location of the split for a branch node (split condition is always "less than").
Yes: ID of the next node when the split condition is met.
No: ID of the next node when the split condition is not met.
Missing: ID of the next node when the branch value is missing.
Gain: either the split gain (change in loss) or the leaf value.
Cover: metric related to the number of observations either seen by a split
or collected by a leaf during training.
When use_int_id = FALSE, columns "Yes", "No", and "Missing" point to model-wide node identifiers
in the "ID" column. When use_int_id = TRUE, those columns point to node identifiers from
the corresponding trees in the "Node" column.
# Basic use:
data(agaricus.train, package = "xgboost")
## Keep the number of threads to 1 for examples
nthread <- 1
data.table::setDTthreads(nthread)
bst <- xgb.train(
data = xgb.DMatrix(agaricus.train$data, label = agaricus.train$label, nthread = 1),
nrounds = 2,
params = xgb.params(
max_depth = 2,
nthread = nthread,
objective = "binary:logistic"
)
)
# This bst model already has feature_names stored with it, so those would be used when
# feature_names is not set:
dt <- xgb.model.dt.tree(bst)
# How to match feature names of splits that are following a current 'Yes' branch:
merge(
dt,
dt[, .(ID, Y.Feature = Feature)], by.x = "Yes", by.y = "ID", all.x = TRUE
)[
order(Tree, Node)
]
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