async-node-astar's Introduction

a-star

Generic synchronous A* search algorithm.

Usage

var aStar = require('a-star');
// if this is going to take a while you may want to child_process.fork
// and pass the results to the parent process
// see below for options
var path = aStar(options);
console.log(path);

Documentation

aStar(options)

Return Value

Returns an object that looks like this:

{
  status: 'success', // one of ['success', 'noPath', 'timeout']
  path: [startNode, node1, node2, ..., endNode],
  cost: cost, // cost of path
}

If status is:

success - a path was found and path is an array of nodes including start and end.
noPath - there is no path from start to end. path is the path to the closest node to end that could be found.
timeout - no path was found in the allotted time. path is the path to the closest node that could be found in the allotted time.

options accepted

start - the start node
isEnd - function(node) that returns whether a node is an acceptable end
neighbor - function(node) that returns an array of neighbors for a node
distance - function(a, b) that returns the distance cost between two nodes
heuristic - function(node) that returns a heuristic guess of the cost from node to an end.
hash - function(node) that returns a unique string for a node. this is so that we can put nodes in heap and set data structures which are based on plain old JavaScript objects. Defaults to using node.toString.
timeout - optional limit to amount of milliseconds to search before returning null.