How we calculate distance between two co-ordinate. ArangoDB

Question

I have a Users table that contains latitude and longitude attribute for every user. So I need to calculate the distance between two users in AQL Query.

I have done the same in Orientdb with the below query.

var laltitude = CURRENT_USER_laltitude;
var longitude = CURRENT_USER_longitude;
var query = "select distance(latitude, longitude,"+laltitude+","+longitude+") as distance from users";

Answer 1

First, create a js file distance.js (or whatever you want to name it) and put below code as below.

/* distance.js */
'use strict';

function gdistance(latitude1, longitude1, latitude2, longitude2, radius) {
    if (!latitude1 || !longitude1 || !latitude2 || !longitude2) { 
        return null; 
    };

    var lat1 = Number(latitude1), lon1 = Number(longitude1);
    var lat2 = Number(latitude2), lon2 = Number(longitude2);

    radius = (radius === undefined) ? 6371e3 : Number(radius);

    var R = radius;
    var φ1 = (lat1 * Math.PI / 180), λ1 = (lon1 * Math.PI / 180);
    var φ2 = (lat2 * Math.PI / 180), λ2 = (lon2 * Math.PI / 180);
    var Δφ = φ2 - φ1;
    var Δλ = λ2 - λ1;

    var a = Math.sin(Δφ/2) * Math.sin(Δφ/2)
          + Math.cos(φ1) * Math.cos(φ2)
          * Math.sin(Δλ/2) * Math.sin(Δλ/2);
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
    var d = R * c;     // Meters
    var d2 = d / 1000; // Meters to KM
    return d2; 
}

module.exports = gdistance;

Now open Arango Console with arangosh . This will open with _system database by default. So if you have other than this database like me then use db._useDatabase("myDatabase") command to change database.

Now write below commands to add custom to your desired database.

Version 2.8

db._useDatabase("myDatabase");
var aqlfunctions = require("org/arangodb/aql/functions");
var f = require("/path/to/file/distance.js");
aqlfunctions.register("geo::gdistance", f, true)

Version 3.0+

db._useDatabase("myDatabase");
var aqlfunctions = require("@arangodb/aql/functions");
var f = require("/path/to/distance.js");

i.e.
var f = require("/home/ubuntu/distance.js");
var f = require("distance.js");

# If you want to remove this group's UDFs (User defined functions)
# aqlfunctions.unregisterGroup("geo");
aqlfunctions.register("geo::gdistance", f, true);

Now use in your AQL queries as below.

LET distance = geo::gdistance(attrbute_name.latitude, attrbute_name.longitude, @your_latitude, @your_longitude)

For more references with here .

Answer 2

Currently ArangoDB can only give you distances when you use the Geo index to return you the distance of your search start to the point matching your condition:

FOR doc IN WITHIN(@@collection, @lat, @long, @radius, @distanceAttributeName)
  RETURN doc

You could however use a user defined AQL function to extend AQL. User defined functions are implemented in Javascript, which is luckily used by Chris Veness to explain howto calculate distances

With ArangoDB 3.0 we most probably will support the arithmetic operations to calculate this in AQL.

I will edit this post with more details and examples soon.