geolib

What is geolib?

The geolib npm package provides a set of functions for common geospatial calculations. It allows you to perform operations such as distance calculations, finding the center of a set of coordinates, and working with bounding boxes.

What are geolib's main functionalities?

Distance Calculation

This feature allows you to calculate the distance between two geographic coordinates. The `getDistance` function returns the distance in meters.

const geolib = require('geolib');
const distance = geolib.getDistance(
  { latitude: 51.5103, longitude: 7.49347 },
  { latitude: 51.515, longitude: 7.453619 }
);
console.log(distance); // Outputs distance in meters

Finding the Center of Coordinates

This feature allows you to find the geographic center of a set of coordinates. The `getCenter` function returns the center coordinate.

const geolib = require('geolib');
const center = geolib.getCenter([
  { latitude: 51.5103, longitude: 7.49347 },
  { latitude: 51.515, longitude: 7.453619 },
  { latitude: 51.525, longitude: 7.470 }
]);
console.log(center); // Outputs the center coordinate

Bounding Box Calculation

This feature allows you to calculate the bounding box for a set of coordinates. The `getBounds` function returns the bounding box.

const geolib = require('geolib');
const bounds = geolib.getBounds([
  { latitude: 51.5103, longitude: 7.49347 },
  { latitude: 51.515, longitude: 7.453619 },
  { latitude: 51.525, longitude: 7.470 }
]);
console.log(bounds); // Outputs the bounding box

Other packages similar to geolib

turf

Turf is a powerful geospatial analysis library that provides a wide range of geospatial functions. It is more comprehensive than geolib and includes advanced features like spatial joins, clustering, and interpolation.

geodesy

Geodesy is a library for geodesic calculations. It provides functions for distance calculations, bearing, and other geospatial operations. It is similar to geolib but focuses more on geodesic calculations.

geokit

Geokit is a library for geospatial calculations and queries. It provides functions for distance calculations, bounding boxes, and other geospatial operations. It is similar to geolib but includes additional features for working with geospatial data in databases.

README

Geolib

A small library to provide some basic geo functions like distance calculation, conversion of decimal coordinates to sexagesimal and vice versa, etc.

View demo

Methods

getDistance(object start, object end, [int accuracy])

Calculates the distance between two geo coordinates

Takes 2 or 3. First 2 arguments must be an object with a latitude and a longitude property (e.g. {latitude: 52.518611, longitude: 13.408056}). Coordinates can be in sexagesimal or decimal format. 3rd argument is accuracy (in meters). So a calculated distance of 1248 meters with an accuracy of 100 is returned as 1200.

Return value is always an integer and represents the distance in meters.

Examples

geolib.getDistance({latitude: 51.5103, longitude: 7.49347}, {latitude: "51° 31' N", longitude: "7° 28' E"});
geolib.getDistance({latitude: 51.5103, longitude: 7.49347}, {latitude: "51° 31' N", longitude: "7° 28' E"});

// Working with W3C Geolocation API
navigator.geolocation.getCurrentPosition(function(position) {
	alert('You are ' + geolib.getDistance(position.coords, {latitude: 51.525, longitude: 7.4575}) + ' meters away from 51.525, 7.4575');
}, function() { alert('Position could not be determined.'), {enableHighAccuracy: true});

getCenter(array coords)

Calculates the geographical center of all points in a collection of geo coordinates

Takes an object or array of coordinates and calculates the center of it.

Returns an object: {"latitude": centerLat, "longitude": centerLng, "distance": diagonalDistance}

Examples

var spots = {
	"Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
	"Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
	"London Eye": {latitude: 51.503333, longitude: -0.119722},
	"Kremlin, Moscow": {latitude: 55.751667, longitude: 37.617778},
	"Eiffel Tower, Paris": {latitude: 48.8583, longitude: 2.2945},
	"Riksdag building, Stockholm": {latitude: 59.3275, longitude: 18.0675},
	"Royal Palace, Oslo": {latitude: 59.916911, longitude: 10.727567}
}

geolib.getCenter(spots);
geolib.getCenter([
	{latitude: 52.516272, longitude: 13.377722}, 
	{latitude: 51.515, longitude: 7.453619}, 
	{latitude: 51.503333, longitude: -0.119722}
]);

isPointInside(object latlng, array coords)

Checks whether a point is inside of a polygon or not. Note: the polygon coords must be in correct order!

Returns true or false

Example

geolib.isPointInside(
	{latitude: 51.5125, longitude: 7.485}, 
	[
		{latitude: 51.50, longitude: 7.40},
		{latitude: 51.555, longitude: 7.40},
		{latitude: 51.555, longitude: 7.625},
		{latitude: 51.5125, longitude: 7.625}
	]
); // -> true

isPointInCircle(object latlng, object center, integer radius)

Similar to is point inside: checks whether a point is inside of a circle or not.

Returns true or false

Example

// checks if 51.525, 7.4575 is within a radius of 5km from 51.5175, 7.4678
geolib.isPointInCircle({latitude: 51.525, longitude: 7.4575}, {latitude: 51.5175, longitude: 7.4678}, 5000);

orderByDistance(object latlng, mixed coords)

Sorts an object or array of coords by distance from a reference coordinate

Returns a sorted array [{latitude: x, longitude: y, distance: z, key: property}]

Examples

// coords array
geolib.orderByDistance({latitude: 51.515, longitude: 7.453619}, [
	{latitude: 52.516272, longitude: 13.377722}, 
	{latitude: 51.518, longitude: 7.45425}, 
	{latitude: 51.503333, longitude: -0.119722}
]);

// coords object
geolib.orderByDistance({latitude: 51.515, longitude: 7.453619}, {
	a: {latitude: 52.516272, longitude: 13.377722}, 
	b: {latitude: 51.518, longitude: 7.45425}, 
	c: {latitude: 51.503333, longitude: -0.119722}
});

findNearest(object latlng, mixed coords, int offset)

Finds the nearest coordinate to a reference coordinate.

Examples

var spots = {
	"Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
	"Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
	"London Eye": {latitude: 51.503333, longitude: -0.119722},
	"Kremlin, Moscow": {latitude: 55.751667, longitude: 37.617778},
	"Eiffel Tower, Paris": {latitude: 48.8583, longitude: 2.2945},
	"Riksdag building, Stockholm": {latitude: 59.3275, longitude: 18.0675},
	"Royal Palace, Oslo": {latitude: 59.916911, longitude: 10.727567}
}

// in this case set offset to 1 otherwise the nearest point will always be your reference point
geolib.findNearest(spots['Dortmund U-Tower'], spots, 1) 

getPathLength(mixed coords)

Calculates the length of a collection of coordinates

Returns the length of the path in kilometers

Example

// Calculate distance from Berlin via Dortmund to London
geolib.getPathLength([
	{latitude: 52.516272, longitude: 13.377722}, // Berlin
	{latitude: 51.515, longitude: 7.453619}, // Dortmund
	{latitude: 51.503333, longitude: -0.119722} // London
]); // -> 945235

convertUnit(string unit, float distance, [int round])

Converts a given distance (in meters) to another unit.

Parameters

unit can be one of:

• m (meter)
• km (kilometers)
• cm (centimeters)
• mm (millimeters)
• mi (miles)
• sm (seamiles)
• ft (foot)
• in (inch)
• yd (yards)

distance distance to be converted (source must be in meter)

round fractional digits

Example

geolib.convertUnit('km', 14213, 2) // -> 14,21

sexagesimal2decimal(string coord)

Converts a sexagesimal coordinate to decimal format

Example

geolib.sexagesimal2decimal("51° 29' 46\" N")

decimal2sexagesimal(float coord)

Converts a decimal coordinate to sexagesimal format

Example

geolib.decimal2sexagesimal(51.49611111); // -> 51° 29' 46.00

useDecimal(mixed coordinate)

Checks if a coordinate is already in decimal format and, if not, converts it to

Example

geolib.useDecimal("51° 29' 46\" N"); // -> 51.59611111
geolib.useDecimal(51.59611111) // -> 51.59611111