CNum::Model::Tree::TreeBooster Class Reference

A decision tree used in various gradient-boosting models as a weak learner. More...

#include <TreeBooster.h>

Inheritance diagram for CNum::Model::Tree::TreeBooster:

Public Member Functions
	TreeBooster (arena_t *a=nullptr, int md=5, int ms=3, double weight_decay=0.0, double reg_lambda=1.0, double gamma=0.0)
	Overloaded default constructor.
	TreeBooster (const TreeBooster &other) noexcept
	Copy constructor.
TreeBooster &	operator= (const TreeBooster &other) noexcept
	Copy equals operator.
	TreeBooster (TreeBooster &&other) noexcept
	Move constructor.
TreeBooster &	operator= (TreeBooster &&other) noexcept
	Move equals operator.
virtual	~TreeBooster ()
	Destructor.
void	set_root (TreeBoosterNode *root)
	Set the root of the tree.
virtual void	fit (DataMatrix &X, std::shared_ptr< CNum::Data::Shelf[]> shelves, double *g, double *h, DataPartition &partition)=0
CNum::DataStructs::Matrix< double >	predict (CNum::DataStructs::Matrix< double > &data)
	Inference (making predictions) on tabular data.
arena_view_t	init_hist_view (size_t n_data_cols)
	Allocate space for histograms on the arena.
std::string	to_json ()
	Save tree data in json encoded string.

Static Public Member Functions
static size_t	partition_data (const CNum::DataStructs::Matrix< int > &X, double *g, double *h, size_t feat, uint8_t bin, const DataPartition &partition)
	Partition idx array, g, and h based on a split to make each nodes' slice of the dataset contigous.
static void	histogram_subtraction (const arena_view_t &parent_hist_view, arena_view_t &small_hist_view, arena_view_t &large_hist_view)
	Subtract a parent histogram from "small" histogram for histogram caching.

Protected Attributes
TreeBoosterNode *	_root
int	_max_depth
int	_min_samples
double	_reg_lambda
double	_gamma
double	_weight_decay
arena_t *	_arena

Detailed Description

A decision tree used in various gradient-boosting models as a weak learner.

The TreeBooster class is a robust and effecient weak learner that is good at recognizing subtle relationships between features in tabular data. While weak on their own when used in gradient-boosting algorithms become extremely powerful.

Constructor & Destructor Documentation

TreeBooster() [1/3]

CNum::Model::Tree::TreeBooster::TreeBooster	(	arena_t *	a = nullptr,
		int	md = 5,
		int	ms = 3,
		double	weight_decay = 0.0,
		double	reg_lambda = 1.0,
		double	gamma = 0.0 )

Overloaded default constructor.

Parameters

a	The arena to use for allocation in this tree (arena of the parent thread in the tree building process)

TreeBooster() [2/3]

CNum::Model::Tree::TreeBooster::TreeBooster ( const TreeBooster & other )

noexcept

Copy constructor.

TreeBooster() [3/3]

CNum::Model::Tree::TreeBooster::TreeBooster ( TreeBooster && other )

noexcept

Move constructor.

~TreeBooster()

virtual CNum::Model::Tree::TreeBooster::~TreeBooster ( )

virtual

Destructor.

Member Function Documentation

fit()

virtual void CNum::Model::Tree::TreeBooster::fit ( DataMatrix & X, std::shared_ptr< CNum::Data::Shelf[]> shelves, double * g, double * h, DataPartition & partition )

pure virtual

Implemented in CNum::Model::Tree::XGTreeBooster.

histogram_subtraction()

void CNum::Model::Tree::TreeBooster::histogram_subtraction ( const arena_view_t & parent_hist_view, arena_view_t & small_hist_view, arena_view_t & large_hist_view )

static

Subtract a parent histogram from "small" histogram for histogram caching.

CNum's tree boosting models exploit histogram caching which reduces the amount of histograms built by building the histogram for the smaller of 2 child node partitions and subtracting it from the parent to yield the larger partition's histogram

Parameters

parent_hist_view	The arena_view_t with the parent histogram
small_hist_view	The arena_view_t with the small partition's histogram
large_hist_view	The arena_view_t that we will fill with the difference of the parent and small histograms

init_hist_view()

arena_view_t CNum::Model::Tree::TreeBooster::init_hist_view

(

size_t

n_data_cols

)

Allocate space for histograms on the arena.

Parameters

n_data_cols

The number of features in the dataset

Returns

An arena_view_t with the histograms

operator=() [1/2]

TreeBooster & CNum::Model::Tree::TreeBooster::operator= ( const TreeBooster & other )

noexcept

Copy equals operator.

operator=() [2/2]

TreeBooster & CNum::Model::Tree::TreeBooster::operator= ( TreeBooster && other )

noexcept

Move equals operator.

partition_data()

size_t CNum::Model::Tree::TreeBooster::partition_data ( const CNum::DataStructs::Matrix< int > & X, double * g, double * h, size_t feat, uint8_t bin, const DataPartition & partition )

static

Partition idx array, g, and h based on a split to make each nodes' slice of the dataset contigous.

Parameters

X	The dataset (row-wise features)
g	The gradient array
h	The hessian array
feat	The feature associated with the split
bin	The bin associated with the split
partition	The current node's data partition

Returns

The index of the boundary between the left and right partitions

predict()

CNum::DataStructs::Matrix< double > CNum::Model::Tree::TreeBooster::predict

(

CNum::DataStructs::Matrix< double > &

data

)

Inference (making predictions) on tabular data.

Parameters

data	The data to make predictions on

Returns

The predictions

set_root()

void CNum::Model::Tree::TreeBooster::set_root

(

TreeBoosterNode *

root

)

Set the root of the tree.

to_json()

std::string CNum::Model::Tree::TreeBooster::to_json

(

)

Save tree data in json encoded string.

Returns

The JSON string

Member Data Documentation

_arena

arena_t* CNum::Model::Tree::TreeBooster::_arena

protected

_gamma

double CNum::Model::Tree::TreeBooster::_gamma

protected

_max_depth

int CNum::Model::Tree::TreeBooster::_max_depth

protected

_min_samples

int CNum::Model::Tree::TreeBooster::_min_samples

protected

_reg_lambda

double CNum::Model::Tree::TreeBooster::_reg_lambda

protected

_root

TreeBoosterNode* CNum::Model::Tree::TreeBooster::_root

protected

_weight_decay

double CNum::Model::Tree::TreeBooster::_weight_decay

protected

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The documentation for this class was generated from the following file:

• include/CNum/Model/Tree/TreeBooster.h