Distance table between CSV coordinates using OSRM

README.md

• Download the Australia OpenStreetMap extract from http://download.openstreetmap.fr/extracts/oceania/australia.osm.pbf
• Build OSRM-Backend https://github.com/Project-OSRM/osrm-backend#quick-start
• osrm-extract -p /usr/local/share/osrm/profiles/car.lua australia.osm.pbf
• osrm-contract australia.osrm
• npm install
• node duration_table.js

duration_table.js

#!/usr/bin/env node

process.env.UV_THREADPOOL_SIZE = Math.ceil(require('os').cpus().length * 1.5);

var OSRM = require('osrm');
var path = require('path');
var fs = require('fs');
var d3 = require('d3');
var async = require('async');
var cheapRuler = require('cheap-ruler');

var osrm = new OSRM("australia.osrm");

// see part 1 at https://gist.github.com/andrewharvey/0248034c0bf098702e13029fd4059a98
var csv = d3.csvParse(fs.readFileSync('sa1_oa_weighted_centroid.csv', 'utf-8'));

var coordinates = csv.map(function (row) {
	return [+row.X, +row.Y];
});

// approximate distance between origin and destination to attempt to calculate a duration for (in kilometers)
var MAX_DISTANCE = 50;

var NUM_THREADS = 4;

var outputFile = fs.createWriteStream('durations.csv');
outputFile.on('error', function (err) { throw err; });

// for each coordinate as the origin and other nearby points as the destinations use osrm.table
async.eachOfLimit(coordinates, NUM_THREADS, function (origin, index, callback) {
	var ruler = cheapRuler(origin[1], 'kilometers');

	var destinationsIndex = []; // keep track of which destinations map to which source coordinates input index
  
  // filter out destinations which are far away from the origin
	var destinations = coordinates.filter(function (destination, index) {
		if (ruler.distance(origin, destination) < MAX_DISTANCE) {
			destinationsIndex.push(index);
			return true;
		}
		return false;
	});

	// ensure the origin is the 1st coordinate pair
	destinations.unshift(origin);
	destinationsIndex.unshift(index);
  
  // duration of the fastest route between all pairs of supplied coordinates
  // http://project-osrm.org/docs/v5.15.2/api/#table-service
	osrm.table({
		coordinates: destinations,
		sources: [0]
	}, function(err, result) {
		if (err) {
			console.error(err)
			callback(err)
			return;
		}

		console.log('From origin ' + index + ' calculated ' + result.durations[0].length + ' distances')

		for (i = 1; i < result.durations[0].length; i++) { // start at 1 to skip source
			if (index !== destinationsIndex[i]) { // no point outputing 0 for self to self
				var output = {
					from: csv[index].sa1_main16,
					to: csv[destinationsIndex[i]].sa1_main16,
					duration: result.durations[0][i]
				};
				outputFile.write(`${output.from},${output.to},${output.duration}\n`);
			}
		}
		callback(err);
	});
},
function (err) {
	if (err) {
		console.error(err);
		return;
	}

	outputFile.end();
	console.log('Saved output to durations.csv')
});

package.json

{
  "name": "duration_table",
  "version": "1.0.0",
  "description": "",
  "main": "duration_table.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Andrew Harvey <andrew@alantgeo.com.au>",
  "license": "ISC",
  "dependencies": {
    "async": "^2.6.1",
    "cheap-ruler": "^2.5.1",
    "d3": "^5.5.0",
    "osrm": "^5.18.0"
  }
}