rouabhi/geolibri

geolibri

geolibri is a simple Node.js package that provides some geo features.

Using package

var geo = require('geolibri');

Available functions

• deg2rad Conversion of degrees to radians.
• rad2deg Radians to degrees conversion.

console.log(" 180° in radians = ",geo.deg2rad(180));
console.log(" 1 radian in degrees = ",geo.rad2deg(1));

• point(...) Creates a point object defined by latitude and longitude.

Possible syntax:

    var P1 = geo.point(latitude, longitude);
    var P2 = geo.point({"latitude":lat , "longitude":lng});
    var P3 = geo.point({"lat":lat , "lng":lng});

We can also give latitude and longitude in radians using *._point(...) instead of .point(...).

It is also possible to initialize a point from another one:

    var P1 = geo.point({latitude:, longitude:});
    var P2 = geo.point(P1); // P2 is at the same position as P1

point() methods

• .lat(), .lng(), .latlng() To get latitude, longitude or a {lat,lng} object.

• ._lat(), ._lng(), , ._latlng() To get latitude or longitude in radians.

• .N( dist ), .E( dist ), .S( dist ), .W( dist ) Returns a new point that is from a distance dist to the North, East, South or West. The distance dist is expressed in meters.

• .O( dist ) Is an alias of .W( dist ) (for the french word Ouest).

• move( dir, distance ) This function moves the current point into the indicated direction and the given distance (in meters). The change is applied to the current point and the returned value is the point itself, to chain functions.

    var P = geo.point(latitude, longitude);
    P.move('N' , 1000 ); // P is moved 1 km to the north
    P.move('E' , 1000 ); // P is then moved 1 km to the east
    P.move('S' , 2350 ).move('W' , 1500 ); // P is now moved 2.35 km to the south and 1.5 km to the west

• .distance( point )

Gives the distance from a point to another one.

    var P = geo.point(lat1, lng1 );
    var Q = geo.point(lat2, lng2 );

    console.log("Distance from P to Q : ",P.distance(Q, unit, precision));

Optional parameters : unit is one of 'm' (meters, default), 'km' (kilometers), 'mile' (miles), 'NM' (nautic miles). Precision is the number of decimals.

This function can also be called this way:

    var geo = require('geolibri');
    var Algiers = geo.point(36.7525000,3.0419700);
    var InGuezzam = geo.point(19.566632, 5.754432)
    console.log("Distance from Algiers(DZ) to In Guezzam(DZ) is : ",geo.distance(Algiers, InGuezzam, "km", 3), " km"); // 1928.06  km

• bounds( dist ) Returns the coordinates of a square with distance dist east, west, north and south of the current point.

    var geo = require('geolibri');
    var InGuezzam = geo.point(19.566632, 5.754432)
    console.log("Coordinates of points 10km arround In Guezzam(DZ): ", InGuezzam.bounds( 10000 ));

Result:

    {
      minlat: 19.476649629499615,
      maxlat: 19.65661437050038,
      minlng: 5.658988084369061,
      maxlng: 5.849982527975235
    }