# Source code for h2o.tree.tree

import math

import h2o

[docs]class H2OTree(object):
"""
Represents a model of a Tree built by one of H2O's tree algorithms (GBM, Random Forest, XGBoost, Isolation Forest).

The internal structure mimics the behavior of Scikit's internal tree representation and contains all the information available about every node in the graph
(https://scikit-learn.org/stable/auto_examples/tree/plot_unveil_tree_structure.html).
It provides both human-readable output and formatting suitable for machine processing.

In the fetched object, there are two representations of the graph contained:

- graph-oriented representation, starting with a root node with edges
- array/vector representation, useful for quick machine processing of the tree’s structure

Every graph starts with a root node. This is an instance of H2OSplitNode and is naturally the very beginning of all decision paths in the graph.
It points to its children, which again point to their children (unless an H2OLeafNode is hit). Nodes are always numbered from the top of the tree down to the lowest level and from left to right.

At the tree level, the following information is provided:

- Number of nodes in the tree
- Model the tree belongs to
- Tree class (if applicable)
- Pointer to a root node for tree traversal (breadth-first, depth-first) and manual tree walking

Each node in the tree is uniquely identified by an ID, regardless of its type. Each node type also has a human-readable description available. There are two types of nodes that are distinguished:

- Split node
- Leaf node

**Split Node**: A split node is a single, non-terminal node with either a numerical or categorical feature split. The root node is guaranteed to be a split node, as a zero-depth tree :math:t of cardinality :math:|t| = 1 contains no decisions at all.
Every split node consists of:

1. An ID or H2O-specific node identifier
2. Left child node & right child node
3. Split feature name (split column name)
4. Split threshold (mainly for numerical splits)
5. Categorical features split (categorical splits only)
6. Direction of NA values (i.e. which way NA values go: left child, right child, or nowhere)

**Leaf Node**: A leaf node is a single node with no children, thus being a terminal node at the end of the decision path in a tree. A leaf node consists of:

1. An ID or H2O-specific node identifier
2. Prediction value (floating point number)

:param model: The model this tree is related to.
:param tree_number: An integer representing the order in which the tree has been built in the model.
:param tree_class: A string representing the name of the tree's class. Specifies the class of the tree requested. Required for multi-class classification.
The number of tree classes equals the number of levels in the categorical response column. As there is exactly one class per categorical level, the name of
the tree's class is equal to the corresponding categorical level of the response column. For regression and binomial models, the name of the categorical level is ignored and can be omitted.
:param plain_language_rules: (Optional) Whether to generate plain language rules. "AUTO" by default, meaning False for big trees and True for small trees.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> # Obtaining a tree is a matter of a single call
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.model_id
>>> tree.tree_number
>>> tree.tree_class

"""

def __init__(self, model, tree_number, tree_class=None, plain_language_rules="AUTO"):
params = {"model": model.model_id,
"tree_number": tree_number,
"tree_class": tree_class,
"plain_language_rules": plain_language_rules}
response = h2o.api(endpoint="GET /3/Tree", data=params)

self._left_children = response['left_children']
self._right_children = response['right_children']
self._node_ids = self.__extract_internal_ids(response['root_node_id'])
self._descriptions = response['descriptions']
self._model_id = model.model_id
self._tree_number = response['tree_number']
self._tree_class = response['tree_class']
self._thresholds = self.__convert_threshold_nans(response['thresholds'])
self._features = response['features']
self._levels = self.__decode_categoricals(model, response['levels'])
self._nas = response['nas']
self._predictions = response['predictions']
self._root_node = self.__assemble_tree(0)
if response['tree_decision_path'] is None:
self._tree_decision_path = "Plain language rules generation is turned off."
self._decision_paths = "Plain language rules generation is turned off."
else:
self._tree_decision_path = response['tree_decision_path']
self._decision_paths = response['decision_paths']

(left, right) = self.__per_node_cat_splits()
self._left_cat_split = left
self._right_cat_split = right

@property
def left_children(self):
"""
An array with left child nodes of tree's nodes.  Holds indices of each node’s left child.

Use the node's ID to obtain the index of the left child for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.left_children
"""
return self._left_children

@property
def right_children(self):
"""
An array with right child nodes of tree's nodes. Holds indices of each node’s right child.

Use node's ID to obtain index of the right child for given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.right_children
"""
return self._right_children

@property
def node_ids(self):
"""
Array with identification numbers of nodes. Node IDs are generated by H2O.
Serves as the node’s unique identifier inside H2O. (May differ from index.)
Nodes are always numbered from the top of the tree down to the lowest level, from left to right.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
"""
return self._node_ids

@property
def descriptions(self):
"""
**Deprecated** please use decision_paths and tree_decision_path instead.
Descriptions for each node to be found in the tree, in human-readable format. Provides a human-readable summary of each node.
Contains split threshold if the split is based on numerical column.
For categorical splits, it contains a list of categorical levels for transition from the parent node.

Use the node's ID to access the description for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.descriptions
"""
return self._descriptions

@property
def model_id(self):
"""
Name (identification) of the model this tree is related to.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.model_id
"""
return self._model_id

@property
def tree_number(self):
"""The order in which the tree has been built in the model.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.tree_number
"""
return self._tree_number

@property
def tree_class(self):
"""The name of a tree's class.

The number of tree classes equals the number of levels in the categorical response column. As there
is exactly one class per categorical level, the name of tree's class is equal to the corresponding
categorical level of the response column.

For regression and binomial models, the name of the categorical level is ignored and can be omitted, as
there is exactly one tree built in both cases.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.tree_class
"""
return self._tree_class

@property
def thresholds(self):
"""
Node split thresholds. Split thresholds are not only related to numerical splits but might be present
in case of categorical split as well.

Use the node's ID to access the threshold for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.thresholds
"""
return self._thresholds

@property
def features(self):
"""
Names of the feature/column used for the split. The array tells which feature is used for the split on a given node.

Use the node's ID to access the split feature for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.features
"""
return self._features

@property
def levels(self):
"""
Categorical levels on the split from the parent's node belonging into this node. None for root node or
non-categorical splits. Show list of categorical levels inherited by each node from the parent.

Use the node's ID to access inherited categorical levels for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.levels
"""
return self._levels

@property
def nas(self):
"""
NA value direction on split. Shows whether NA values go to the left node or the right node. The value may be None if the node is a leaf
or if there is no possibility of an NA value occuring during a split, typically due to filtering all NAs out to a different path in the graph.

Use the node's ID to access NA direction for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.nas
"""
return self._nas

@property
def root_node(self):
"""An instance of H2ONode representing the beginning of the tree behind the model.
Allows further tree traversal.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.root_node
"""
return self._root_node

@property
def predictions(self):
"""
Values predicted on tree's nodes.

Use the node's ID to access predictions for a given node in the underlying array.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.predictions
"""
return self._predictions

@property
def tree_decision_path(self):
return self._tree_decision_path

@property
def decision_paths(self):
return self._decision_paths

def __convert_threshold_nans(self, thresholds):
for i in range(0, len(thresholds)):
if thresholds[i] == "NaN": thresholds[i] = float('nan')
return thresholds

def __assemble_tree(self, node):
if node == -1: return None

left_child = self._left_children[node]
right_child = self._right_children[node]

if left_child == -1 and right_child == -1:
return H2OLeafNode(node_id=self._node_ids[node],
prediction=self._predictions[node])
else:
return H2OSplitNode(node_id=self._node_ids[node],
left_child=self.__assemble_tree(left_child),
right_child=self.__assemble_tree(right_child),
threshold=self._thresholds[node],
split_feature=self._features[node],
na_direction=self._nas[node],
left_levels=self._levels[left_child],
right_levels = self._levels[right_child])

def __decode_categoricals(self, model, levels):
string_levels = len(self._left_children) * [None]

if model.algo == 'xgboost':
return string_levels

for i in range(0, len(self._left_children)):
if (self._features[i] is None): continue
left_node = self._left_children[i]
right_node = self._right_children[i]
split_column_index = model._model_json["output"]["names"].index(self._features[i])
domain = model._model_json["output"]["domains"][split_column_index]
if domain is None: continue

if left_node != -1:
left_levels = []
if levels[left_node] is not None:
for lvl_index in levels[left_node]:
left_levels.append(domain[lvl_index])

string_levels[left_node] = left_levels

if right_node != -1:
right_levels = []
if levels[right_node] is not None:
for lvl_index in levels[right_node]:
right_levels.append(domain[lvl_index])

string_levels[right_node] = right_levels

return string_levels

def __extract_internal_ids(self, root_node_id):
node_index = 0
node_ids = [root_node_id]
for i in range(0, len(self._left_children)):
if (self._left_children[i] != -1):
node_index = node_index + 1
node_ids.append(self._left_children[i])
self._left_children[i] = node_index
else:
self._left_children[i] = -1

if (self._right_children[i] != -1):
node_index = node_index + 1
node_ids.append(self._right_children[i])
self._right_children[i] = node_index
else:
self._right_children[i] = -1

return node_ids

def __per_node_cat_splits(self):

num_records = len(self.left_children)
per_node_levels_left = [None] * num_records
per_node_levels_right = [None] * num_records
for i in range(0, (len(self.left_children))):

# -1 means leaf - if a node is leaf node, there is not child and thus no split
left_idx = self._left_children[i]
right_idx = self._right_children[i]

if (left_idx != -1):
per_node_levels_left[i] = (self.levels[left_idx])

if (right_idx != -1):
per_node_levels_right[i] = (self.levels[right_idx])

return (per_node_levels_left, per_node_levels_right)

@property
def left_cat_split(self):
"""
:return: Categorical levels leading to the left child node. Only present when split is categorical, otherwise none.
"""
return self._left_cat_split

@property
def right_cat_split(self):
"""

:return: Categorical levels leading to the right child node. Only present when split is categorical, otherwise none.

"""
return self._right_cat_split

def __len__(self):
"""
Returns number of nodes inside the tree.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> len(tree)
"""
return len(self._node_ids)

def __str__(self):
return "Tree related to model {}. Tree number is {}, tree class is '{}'\n\n".format(self._model_id,
self._tree_number,
self._tree_class)
[docs]    def show(self):
"""Summarizes the H2OTree.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.show()
"""
print(self.__str__())

[docs]class H2ONode():
"""
Represents a single abstract node in an H2OTree.

:param id: Node's unique identifier (integer). Generated by H2O.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2ONode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
"""

def __init__(self, node_id):
self._id = node_id

@property
def id(self):
"""Node's unique identifier (integer). Generated by H2O.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2ONode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
>>> node0 = H2ONode(0)
>>> node0
"""
return self._id

def __str__(self):
return "Node ID {} \n".format(self._id)

[docs]class H2OLeafNode(H2ONode):
"""
Represents a single terminal node in an H2OTree with final prediction.

:param id: Node's unique identifier (integer). Generated by H2O.
:param prediction: The prediction value in the terminal node (numeric floating point).

:examples:

>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OLeafNode
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
# Retrieve the node ids
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
# Retrieve the predictions
>>> tree.predictions
# Set the id and prediction
>>> H2OLeafNode(0, -0.23001842)
"""

def __init__(self, node_id, prediction):
H2ONode.__init__(self, node_id)
self._prediction = prediction

@property
def id(self):
"""Node's unique identifier (integer). Generated by H2O.

:examples:

>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OLeafNode
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
# Retrieve the node ids
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
# Retrieve the predictions
>>> tree.predictions
# Set the id and prediction
>>> leaf_node = H2OLeafNode(0, -0.23001842)
# Retrieve the node id
>>> leaf_node.id
"""
return self._id

@property
def prediction(self):
"""Prediction value in the terminal node (numeric floating point).

:examples:

>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OLeafNode
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
# Retrieve the node ids
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.node_ids
# Retrieve the predictions
>>> tree.predictions
# Set the id and prediction
>>> leaf_node = H2OLeafNode(0, -0.23001842)
# Retrieve the node prediction
>>> leaf_node.prediction
"""
return self._prediction

def __str__(self):
return "Leaf node ID {}. Predicted value at leaf node is {} \n".format(self._id, self._prediction)

[docs]    def show(self):
"""
:examples:

>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OLeafNode
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin", "Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
# Retrieve the predictions
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> tree.predictions
# Retrieve predicted value for a node
>>> leaf_node = H2OLeafNode(0, -0.23001842)
>>> leaf_node.show()
"""
print(self.__str__())

[docs]class H2OSplitNode(H2ONode):
"""
Represents a single node with either numerical or categorical split in an H2OTree with all its attributes.

:param id: Node's unique identifier (integer). Generated by H2O.
:param threshold: Split threshold, typically when the split column is numerical.
:param left_child: Integer identifier of the left child node, if there is any. Otherwise None.
:param right_child: Integer identifier of the right child node, if there is any. Otherwise None.
:param split_feature: The name of the column this node splits on.
:param na_direction: The direction of NA values. LEFT means NA values go to the left child node; RIGHT means NA values go to the right child node. A value of None means occurence of NA for the given split column is not possible on this node due to an earlier split on the very same feature.
:param left_levels: Categorical levels on the edge from this node to the left child node. None for non-categorical splits.
:param right_levels: Categorical levels on the edge from this node to the right child node. None for non-categorical splits.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> H2OSplitNode(5, threshold, left_child,
...              right_child, split_feature,
...              na_direction, left_levels,
...              right_levels)
"""

def __init__(self, node_id, threshold, left_child, right_child, split_feature, na_direction, left_levels, right_levels):
H2ONode.__init__(self, node_id)
self._threshold = threshold
self._left_child = left_child
self._right_child = right_child
self._split_feature = split_feature
self._na_direction = na_direction
self._left_levels = left_levels
self._right_levels = right_levels

@property
def id(self):
"""Node's unique identifier (integer). Generated by H2O.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.id
"""
return self._id

@property
def threshold(self):
"""
Split threshold for each node. Not only numerical features have numerical split. For splits on categorical features,
the numerical split threshold represents an index in the categorical feature's domain.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.threshold
"""
return self._threshold

@property
def left_child(self):
"""
Integer identifier of the left child node, if there is any. Otherwise None.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.left_child
"""
return self._left_child

@property
def right_child(self):
"""Integer identifier of the right child node, if there is any. Otherwise None.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.right_child
"""
return self._right_child

@property
def split_feature(self):
"""The name of the column this node splits on.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.split_feature
"""
return self._split_feature

@property
def na_direction(self):
"""
The direction of NA values. LEFT means NA values go to the left child node; RIGHT means NA values go to the right child node. A value of None means occurance of NA for the given split column is not possible on this node due to an earlier split on the very same feature.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.na_direction
"""
return self._na_direction

@property
def left_levels(self):
"""
Categorical levels on the edge from this node to the left child node. None for non-categorical splits.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.left_levels
"""
return self._left_levels

@property
def right_levels(self):
"""
Categorical levels on the edge from this node to the right child node. None for non-categorical splits.

:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.right_levels
"""
return self._right_levels

def __str__(self):
out = "Node ID {} \n".format(self._id)
if self._split_feature is not None:
if self._left_child is not None:
out += "Left child node ID = {}\n".format(self.left_child.id)
else:
out += "There is no left child\n"
if self._right_child is not None:
out += "Right child node ID = {}\n".format(self.right_child.id)
else:
out += "There is no right child\n"

out += "\nSplits on column {}\n".format(self._split_feature)

else:
out += "This is a terminal node"

if math.isnan(self._threshold):
if self._left_child is not None:
out += "  - Categorical levels going to the left node: {}\n".format(self._left_levels)
if self._right_child is not None:
out += "  - Categorical levels going to the right node: {}\n".format(self._right_levels)

else:
out += "Split threshold < {} to the left node, >= {} to the right node \n".format(self._threshold,
self._threshold)

if self._na_direction is not None: out += "\nNA values go to the {}".format(self._na_direction)

return out

[docs]    def show(self):
"""
:examples:

>>> from h2o.tree import H2OTree
>>> from h2o.tree import H2OSplitNode
>>> from h2o.estimators import H2OGradientBoostingEstimator
>>> airlines = h2o.import_file("https://s3.amazonaws.com/h2o-public-test-data/smalldata/airlines/AirlinesTrain.csv")
>>> gbm = H2OGradientBoostingEstimator(ntrees=1)
>>> gbm.train(x=["Origin","Dest"],
...           y="IsDepDelayed",
...           training_frame=airlines)
>>> tree = H2OTree(model = gbm, tree_number = 0 , tree_class = "NO")
>>> threshold = 'nan'
>>> left_child = 9
>>> right_child = 10
>>> split_feature = "DepTime"
>>> na_direction = "Left"
>>> left_levels = ['FAT', 'LAS', 'PSP']
>>> right_levels = ['BWI', 'CLT', 'IND', 'MCO',
...                 'PHL', 'PHX', 'RIC', 'TPA']
>>> split_node = H2OSplitNode(5, threshold, left_child,
...                           right_child, split_feature,
...                           na_direction, left_levels,
...                           right_levels)
>>> split_node.show
"""
print(self)