@sabaki/influence

Simple static heuristics for estimating influence maps on Go positions.

Installation

Use npm to install:

$ npm install @sabaki/influence

Then require it as follows:

const influence = require('@sabaki/influence');

API

Board Data

The board arrangement is represented by an array of arrays. Each of those subarrays represent one row, all containing the same number of integers. -1 denotes a white stone, 1 a black stone, and 0 represents an empty vertex

Example

[[ 0,  0,  1,  0, -1, -1,  1,  0, 0],
 [ 1,  0,  1, -1, -1,  1,  1,  1, 0],
 [ 0,  0,  1, -1,  0,  1, -1, -1, 0],
 [ 1,  1,  1, -1, -1, -1,  1, -1, 0],
 [ 1, -1,  1,  1, -1,  1,  1,  1, 0],
 [-1, -1, -1, -1, -1,  1,  0,  0, 0],
 [ 0, -1, -1,  0, -1,  1,  1,  1, 1],
 [ 0,  0,  0,  0,  0, -1, -1, -1, 1],
 [ 0,  0,  0,  0,  0,  0,  0, -1, 0]]

influence.map(data[, options])

• data - Board data
• options <Object> (optional)

  • discrete <Boolean> (optional) - Default: false

  • maxDistance <Number> (optional) - Default: 6

    Only assigns a non-zero number to a vertex if its Manhattan distance to a stone of corresponding color is less or equal to maxDistance.

  • minRadiance <Number> (optional) - Default: 2

    Only assigns a non-zero number to a vertex if the vertex has radiance in its corresponding color greater or equal to minRadiance.

Returns an array of arrays of the same size as data. Each entry is a number between -1 and 1 inclusive. A negative number corresponds to white influence whereas a positive number denotes black influence.

This map does not take dead stones into account, i.e. it will assume all stones specified in data are alive. To get better results, remove dead stones first, either manually or with the deadstones module.

If discrete is set to true, the map will only contain -1, 0, or 1 as values.

influence.areaMap(data)

• data - Board data

Returns an array of arrays of the same size as data. Each entry is either -1, 0, or 1, corresponding to white area, neutral area, and black area.

influence.nearestNeighborMap(data, sign)

• data - Board data
• sign -1 | 1

Returns an array of arrays of the same size as data. Each entry is an non-negative integer which denotes the Manhattan distance to the nearest stone with the color given by sign. -1 denotes white and 1 corresponds to black.

influence.radianceMap(data, sign[, options])

• data - Board data
• sign -1 | 1
• options <Object> (optional)
  • p1 <Number> (optional) - Default: 6
  • p2 <Number> (optional) - Default: 1.5
  • p3 <Number> (optional) - Default: 2

Returns an array of arrays of the same size as data. Each entry is a non-negative number which encodes how many stones of the color corresponding to sign is in its vicinity. -1 corresponds to white stones whereas 1 denotes black stones. Each chain of the color corresponding to sign emits radiance which diminishes over distance, adds up with the radiance of other chains, and reflects at the board edge.

p1, p2, and p3 are parameters, controlling how strong the radiance is initially and how it diminishes.