xgb.model.dt.tree
Parse a boosted tree model text dump
Parse a boosted tree model text dump into a data.table
structure.
Usage
xgb.model.dt.tree(
feature_names = NULL,
model = NULL,
text = NULL,
trees = NULL,
use_int_id = FALSE,
...
)
Arguments
- feature_names
character vector of feature names. If the model already contains feature names, those would be used when
feature_names=NULL
(default value). Non-nullfeature_names
could be provided to override those in the model.- model
object of class
xgb.Booster
- text
character
vector previously generated by thexgb.dump
function (where parameterwith_stats = TRUE
should have been set).text
takes precedence overmodel
.- trees
an integer vector of tree indices that should be parsed. If set to
NULL
, all trees of the model are parsed. It could be useful, e.g., in multiclass classification to get only the trees of one certain class. IMPORTANT: the tree index in xgboost models is zero-based (e.g., usetrees = 0:4
for first 5 trees).- use_int_id
a logical flag indicating whether nodes in columns "Yes", "No", "Missing" should be represented as integers (when FALSE) or as "Tree-Node" character strings (when FALSE).
- ...
currently not used.
Value
A data.table
with detailed information about model trees' nodes.
The columns of the data.table
are:
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 whenuse_int_id=FALSE
)Feature
: for a branch node, it's a feature id or name (when available); for a leaf note, 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 metNo
: ID of the next node when the split condition is not metMissing
: ID of the next node when branch value is missingQuality
: either the split gain (change in loss) or the leaf valueCover
: metric related to the number of observation 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.
Examples
# NOT RUN {
# Basic use:
data(agaricus.train, package='xgboost')
bst <- xgboost(data = agaricus.train$data, label = agaricus.train$label, max_depth = 2,
eta = 1, nthread = 2, nrounds = 2,objective = "binary:logistic")
(dt <- xgb.model.dt.tree(colnames(agaricus.train$data), bst))
# 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(model = 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)]
# }