ShapAlgo2

Full name Microsoft.VisualBasic.Math.Statistics.ShapleyValue.TreeShap.ShapAlgo2 Assembly Microsoft.VisualBasic.Math.Statistics Members 3

Rewrite of the Algorithm 2 from [1].

The main goal here is to get "fanatically faithful" transcript of the algo into java. Therefore, performance and memory optimizations are neither done nor planned here.

Deviations from original notation:

java list/arrays are zero-based
tree is represented by recursive structure of nodes, each is either a leaf or a split node with yes, no, and other props
the path (stored in variable "m") has long-named properties to make the thing more readable

Bugfixes:

[bugfix1] in EXTEND, iteration misses newly added element, causing wrong computation - see [2]
[bugfix2] in UNWIND, iteration exceeds into removed element, causing exception

Resources:

[1] Consistent Individualized Feature Attribution for Tree Ensembles - https://arxiv.org/pdf/1802.03888.pdf
[2] From local explanations to global understanding with explainable AI for trees, pages 65,66 - https://www.nature.com/articles/s42256-019-0138-9.epdf?shared_access_token=RCYPTVkiECUmc0CccSMgXtRgN0jAjWel9jnR3ZoTv0O81kV8DqPb2VXSseRmof0Pl8YSOZy4FHz5vMc3xsxcX6uT10EzEoWo7B-nZQAHJJvBYhQJTT1LnJmpsa48nlgUWrMkThFrEIvZstjQ7Xdc5g%3D%3D

00 Remarks

https://github.com/pkozelka/treeshap

01 Syntax

Microsoft.VisualBasic.Math.Statistics.ShapleyValue.TreeShap.ShapAlgo2

02 Methods

Name	Overloads	Summary
unwind	1	Removes i-th element of the path, and redistributes all weights
compute	1

03 Fields

Name	Overloads	Summary
DEBUG	1

04 Members

method unwind #

unwind(IList(Of PathElement), Int32)

Removes i-th element of the path, and redistributes all weights

Parameters

Name	Type	Description
`origM`	`IList(Of PathElement)`	elements of decision path
`i`	`Int32`	zero-based index to be removed

Returns

transformed decision path

field DEBUG #

DEBUG

method compute #

compute(Double(), PkTree)