# Geolib
[](http://travis-ci.org/manuelbieh/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](http://www.manuel-bieh.de/publikationen/scripts/geolib/demo.html)
Methods
geolib.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
}
);
geolib.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}
]);
geolib.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
geolib.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
);
geolib.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}
});
geolib.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)
geolib.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
geolib.getSpeed(coords, coords[, options])
Calculates the speed between to points within a given time span.
Returns the speed in options.unit (default is km/h).
Example
geolib.getSpeed(
{lat: 51.567294, lng: 7.38896, time: 1360231200880},
{lat: 52.54944, lng: 13.468509, time: 1360245600880},
{unit: 'mph'}
); // -> 66.9408 (mph)
geolib.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`
geolib.sexagesimal2decimal(string coord)
Converts a sexagesimal coordinate to decimal format
Example
`geolib.sexagesimal2decimal("51° 29' 46\" N")`
geolib.decimal2sexagesimal(float coord)
Converts a decimal coordinate to sexagesimal format
Example
`geolib.decimal2sexagesimal(51.49611111); // -> 51° 29' 46.00`
geolib.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