mlpack::rl::SumTree< T > Class Template Reference

Implementation of SumTree. More...

#include <sumtree.hpp>

Public Member Functions
	SumTree ()
	Default constructor.
	SumTree (const size_t capacity)
	Construct an instance of SumTree class. More...
void	Set (size_t idx, const T value)
	Set the data array with idx. More...
void	BatchUpdate (const arma::ucolvec &indices, const arma::Col< T > &data)
	Update the data with batch rather loop over the indices with set method. More...
T	Get (size_t idx)
	Get the data array with idx. More...
T	SumHelper (const size_t start, const size_t end, const size_t node, const size_t nodeStart, const size_t nodeEnd)
	Help function for the sum function. More...
T	Sum (const size_t start, size_t end)
	Calculate the sum of contiguous subsequence of the array. More...
T	Sum ()
	Shortcut for calculating the sum of whole array.
size_t	FindPrefixSum (T mass)
	Find the highest index idx in the array such that sum(arr[0] + arr[1] + ... More...

Detailed Description

template<typename T>
class mlpack::rl::SumTree< T >

Implementation of SumTree.

Build a Segment Tree like data structure. https://en.wikipedia.org/wiki/Segment_tree

Used to maintain prefix-sum of an array.

Template Parameters

T	The array's element type.

Constructor & Destructor Documentation

SumTree()

template<typename T>

mlpack::rl::SumTree< T >::SumTree ( const size_t  capacity )

inline

Construct an instance of SumTree class.

Parameters

capacity

Size of data.

Member Function Documentation

BatchUpdate()

template<typename T>

void mlpack::rl::SumTree< T >::BatchUpdate ( const arma::ucolvec &  indices, const arma::Col< T > &  data  )

inline

Update the data with batch rather loop over the indices with set method.

Parameters

indices	The indices of data to be changed.
data	The data that array with indices to be.

FindPrefixSum()

template<typename T>

size_t mlpack::rl::SumTree< T >::FindPrefixSum ( T  mass )

inline

Find the highest index idx in the array such that sum(arr[0] + arr[1] + ...

• arr[idx]) <= mass.

Parameters

mass	The upper bound of segment array sum.

Get()

template<typename T>

T mlpack::rl::SumTree< T >::Get ( size_t  idx )

inline

Get the data array with idx.

Parameters

idx	The array idx to get data.

Set()

template<typename T>

void mlpack::rl::SumTree< T >::Set ( size_t  idx, const T  value  )

inline

Set the data array with idx.

Parameters

idx	The array idx to be changed.
value	The data that array with idx to be.

Sum()

template<typename T>

T mlpack::rl::SumTree< T >::Sum ( const size_t  start, size_t  end  )

inline

Calculate the sum of contiguous subsequence of the array.

Parameters

start	The starting position of subsequence.
end	The end position of subsequence.

SumHelper()

template<typename T>

T mlpack::rl::SumTree< T >::SumHelper ( const size_t  start, const size_t  end, const size_t  node, const size_t  nodeStart, const size_t  nodeEnd  )

inline

Help function for the sum function.

Parameters

start	The starting position of subsequence.
end	The end position of subsequence.
node	Reference position.
nodeStart	Starting position of reference segment.
nodeEnd	End position of reference segment.

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

• src/mlpack/methods/reinforcement_learning/replay/sumtree.hpp