404 lines
13 KiB
Markdown
404 lines
13 KiB
Markdown
# Geolib v2.0.21
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[](http://travis-ci.org/manuelbieh/Geolib)
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Library to provide basic geospatial operations like distance calculation, conversion of decimal coordinates to sexagesimal and vice versa, etc.
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[View demo](http://www.manuel-bieh.de/publikationen/scripts/geolib/demo.html)
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<h2>Methods</h2>
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<h3>geolib.getDistance(object start, object end[, int accuracy, int precision])</h3>
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Calculates the distance between two geo coordinates
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Takes 2 or 4 arguments. First 2 arguments must be objects that each have latitude and longitude properties (e.g. `{latitude: 52.518611, longitude: 13.408056}`)Works with:. Coordinates can be in sexagesimal or decimal format. 3rd argument is accuracy (in meters). So a calculated distaWorks with:nce of 1248 meters with an accuracy of 100 is returned as `1200` (accuracy 10 = `1250` etc.). 4th argument is precision in sub-meters (1 is meter presicion, 2 is decimeters, 3 is centimeters, etc).
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Return value is always float and represents the distance in meters.
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<h4>Examples</h4>
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<pre>geolib.getDistance(
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{latitude: 51.5103, longitude: 7.49347},
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{latitude: "51° 31' N", longitude: "7° 28' E"}
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);
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geolib.getDistance(
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{latitude: 51.5103, longitude: 7.49347},
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{latitude: "51° 31' N", longitude: "7° 28' E"}
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);
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// Working with W3C Geolocation API
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navigator.geolocation.getCurrentPosition(
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function(position) {
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alert('You are ' + geolib.getDistance(position.coords, {
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latitude: 51.525,
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longitude: 7.4575
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}) + ' meters away from 51.525, 7.4575');
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},
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function() {
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alert('Position could not be determined.')
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},
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{
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enableHighAccuracy: true
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}
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);
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</pre>
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<h3>geolib.getDistanceSimple(object start, object end[, int accuracy])</h3>
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Calculates the distance between two geo coordinates but this method is far more inaccurate as compared to getDistance.
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It can take up 2 to 3 arguments. start, end and accuracy can be defined in the same as in getDistance.
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Return value is always float that represents the distance in meters.
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<h4>Examples</h4>
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<pre>geolib.getDistanceSimple(
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{latitude: 51.5103, longitude: 7.49347},
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{latitude: "51° 31' N", longitude: "7° 28' E"}
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);</pre>
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<h3>geolib.getCenter(array coords)</h3>
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Calculates the geographical center of all points in a collection of geo coordinates
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Takes an object or array of coordinates and calculates the center of it.
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Returns an object: `{"latitude": centerLat, "longitude": centerLng}`
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<h4>Examples</h4>
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<pre>var spots = {
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"Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
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"Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
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"London Eye": {latitude: 51.503333, longitude: -0.119722},
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"Kremlin, Moscow": {latitude: 55.751667, longitude: 37.617778},
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"Eiffel Tower, Paris": {latitude: 48.8583, longitude: 2.2945},
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"Riksdag building, Stockholm": {latitude: 59.3275, longitude: 18.0675},
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"Royal Palace, Oslo": {latitude: 59.916911, longitude: 10.727567}
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}
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geolib.getCenter(spots);
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geolib.getCenter([
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{latitude: 52.516272, longitude: 13.377722},
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{latitude: 51.515, longitude: 7.453619},
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{latitude: 51.503333, longitude: -0.119722}
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]);
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</pre>
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<h3>geolib.getCenterOfBounds(array coords)</h3>
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Calculates the center of the bounds of geo coordinates.
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Takes an array of coordinates, calculate the border of those, and gives back
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the center of that rectangle.
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On polygons like political borders (eg. states), this may gives a closer
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result to human expectation, than `getCenter`, because that function can be
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disturbed by uneven distribution of point in different sides.
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Imagine the US state Oklahoma: `getCenter` on that gives a southern
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point, because the southern border contains a lot more nodes, than the others.
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Returns an object: `{"latitude": centerLat, "longitude": centerLng}`
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<h3>geolib.getBounds(array coords)</h3>
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Calculates the bounds of geo coordinates.
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It returns maximum and minimum, latitude, longitude, and elevation (if provided) in form of an object of form:
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<pre>{
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"minLat": minimumLatitude,
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"maxLat": maximumLatitude,
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"minLng": minimumLongitude,
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"maxLng": maximumLongitude,
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"minElev": minimumElevation,
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"maxElev": maximumElevation
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}</pre>
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<h4>Example</h4>
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<pre>geolib.getCenter([
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{latitude: 52.516272, longitude: 13.377722},
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{latitude: 51.515, longitude: 7.453619},
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{latitude: 51.503333, longitude: -0.119722}
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]);</pre>
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<h3>geolib.isPointInside(object latlng, array polygon)</h3>
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Checks whether a point is inside of a polygon or not.
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Note: the polygon coords must be in correct order!
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Returns true or false
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<h4>Example</h4>
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<pre>
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geolib.isPointInside(
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{latitude: 51.5125, longitude: 7.485},
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[
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{latitude: 51.50, longitude: 7.40},
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{latitude: 51.555, longitude: 7.40},
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{latitude: 51.555, longitude: 7.625},
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{latitude: 51.5125, longitude: 7.625}
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]
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); // -> true</pre>
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<h3>geolib.isPointInCircle(object latlng, object center, integer radius)</h3>
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Similar to is point inside: checks whether a point is inside of a circle or not.
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Returns true or false
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<h4>Example</h4>
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<pre>// checks if 51.525, 7.4575 is within a radius of 5km from 51.5175, 7.4678
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geolib.isPointInCircle(
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{latitude: 51.525, longitude: 7.4575},
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{latitude: 51.5175, longitude: 7.4678},
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5000
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);</pre>
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<h3>geolib.getRhumbLineBearing(object originLL, object destLL)</h3>
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Gets rhumb line bearing of two points. Find out about the difference between rhumb line and
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great circle bearing on Wikipedia. Rhumb line should be fine in most cases:
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http://en.wikipedia.org/wiki/Rhumb_line#General_and_mathematical_description
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Function is heavily based on Doug Vanderweide's great PHP version (licensed under GPL 3.0)
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http://www.dougv.com/2009/07/13/calculating-the-bearing-and-compass-rose-direction-between-two-latitude-longitude-coordinates-in-php/
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Returns calculated bearing as integer.
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<h4>Example</h4>
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<pre>geolib.getRhumbLineBearing(
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{latitude: 52.518611, longitude: 13.408056},
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{latitude: 51.519475, longitude: 7.46694444}
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);</pre>
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<h3>geolib.getBearing(object originLL, object destLL)</h3>
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Gets great circle bearing of two points. See description of getRhumbLineBearing for more information.
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Returns calculated bearing as integer.
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<h4>Example</h4>
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<pre>geolib.getBearing(
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{latitude: 52.518611, longitude: 13.408056},
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{latitude: 51.519475, longitude: 7.46694444}
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);</pre>
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<h3>geolib.getCompassDirection(object originLL, object destLL, string bearingMode (optional))</h3>
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Gets the compass direction from an origin coordinate (originLL) to a destination coordinate (destLL).
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Bearing mode. Can be either circle or rhumbline (default).
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Returns an object with a rough (NESW) and an exact direction (NNE, NE, ENE, E, ESE, etc).
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<h4>Example</h4>
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<pre>geolib.getCompassDirection(
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{latitude: 52.518611, longitude: 13.408056},
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{latitude: 51.519475, longitude: 7.46694444}
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);
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//Output
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{
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rough: 'W',
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exact: 'WSW'
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}</pre>
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<h3>geolib.orderByDistance(object latlng, mixed coords)</h3>
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Sorts an object or array of coords by distance from a reference coordinate
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Returns a sorted array [{latitude: x, longitude: y, distance: z, key: property}]
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<h4>Examples</h4>
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<pre>
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// coords array
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geolib.orderByDistance({latitude: 51.515, longitude: 7.453619}, [
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{latitude: 52.516272, longitude: 13.377722},
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{latitude: 51.518, longitude: 7.45425},
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{latitude: 51.503333, longitude: -0.119722}
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]);
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// coords object
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geolib.orderByDistance({latitude: 51.515, longitude: 7.453619}, {
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a: {latitude: 52.516272, longitude: 13.377722},
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b: {latitude: 51.518, longitude: 7.45425},
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c: {latitude: 51.503333, longitude: -0.119722}
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});
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</pre>
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<h3>geolib.findNearest(object latlng, mixed coords[[, int offset], int limit])</h3>
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Finds the nearest coordinate to a reference coordinate.
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<h4>Examples</h4>
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<pre>var spots = {
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"Brandenburg Gate, Berlin": {latitude: 52.516272, longitude: 13.377722},
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"Dortmund U-Tower": {latitude: 51.515, longitude: 7.453619},
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"London Eye": {latitude: 51.503333, longitude: -0.119722},
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"Kremlin, Moscow": {latitude: 55.751667, longitude: 37.617778},
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"Eiffel Tower, Paris": {latitude: 48.8583, longitude: 2.2945},
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"Riksdag building, Stockholm": {latitude: 59.3275, longitude: 18.0675},
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"Royal Palace, Oslo": {latitude: 59.916911, longitude: 10.727567}
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}
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// in this case set offset to 1 otherwise the nearest point will always be your reference point
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geolib.findNearest(spots['Dortmund U-Tower'], spots, 1)
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</pre>
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<h3>geolib.getPathLength(mixed coords)</h3>
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Calculates the length of a collection of coordinates
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Returns the length of the path in meters
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<h4>Example</h4>
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<pre>
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// Calculate distance from Berlin via Dortmund to London
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geolib.getPathLength([
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{latitude: 52.516272, longitude: 13.377722}, // Berlin
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{latitude: 51.515, longitude: 7.453619}, // Dortmund
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{latitude: 51.503333, longitude: -0.119722} // London
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]); // -> 945235</pre>
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<h3>geolib.getSpeed(coords, coords[, options])</h3>
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Calculates the speed between two points within a given time span.
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Returns the speed in <em>options.unit</em> (default is km/h).
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<h4>Example</h4>
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<pre>
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geolib.getSpeed(
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{lat: 51.567294, lng: 7.38896, time: 1360231200880},
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{lat: 52.54944, lng: 13.468509, time: 1360245600880},
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{unit: 'mph'}
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); // -> 66.9408 (mph)</pre>
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<h3>geolib.isPointInLine(object point, object start, object end</h3>
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Calculates if given point lies in a line formed by start and end.
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Returns true or false
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<h4>Examples</h4>
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<pre>var point1 = {latitude: 0.5, longitude: 0};
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var point2 = {latitude: 0, longitude: 10};
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var point3 = {latitude: 0, longitude: 15.5};
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var start = {latitude: 0, longitude: 0};
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var end = {latitude: 0, longitude: 15};
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var isInLine1 = geolib.isPointInLine(point1, start, end) //-> false;
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var isInLine2 = geolib.isPointInLine(point2, start, end) //-> true;
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var isInLine3 = geolib.isPointInLine(point3, start, end) //-> false;
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</pre>
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<h3>geolib.convertUnit(string unit, float distance[, int round])</h3>
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Converts a given distance (in meters) to another unit.
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<h4>Parameters</h4>
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`unit` can be one of:
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- m (meter)
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- km (kilometers)
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- cm (centimeters)
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- mm (millimeters)
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- mi (miles)
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- sm (seamiles)
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- ft (foot)
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- in (inch)
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- yd (yards)
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`distance` distance to be converted (source must be in meter)
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`round` fractional digits
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<h4>Example</h4>
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`geolib.convertUnit('km', 14213, 2) // -> 14,21`
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<h3>geolib.sexagesimal2decimal(string coord)</h3>
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Converts a sexagesimal coordinate to decimal format
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<h4>Example</h4>
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`geolib.sexagesimal2decimal("51° 29' 46\" N")`
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<h3>geolib.decimal2sexagesimal(float coord)</h3>
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Converts a decimal coordinate to sexagesimal format
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<h4>Example</h4>
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`geolib.decimal2sexagesimal(51.49611111); // -> 51° 29' 46.00`
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<h3>geolib.latitude(object latlng)</h3>
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<h3>geolib.longitude(object latlng)</h3>
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<h3>geolib.elevation(object latlng)</h3>
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Returns the latitude/longitude/elevation for a given point and converts it to decimal.
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Works with:
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- longitude: `longitude`, `lng`, `lon`, 0 (GeoJSON array)
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- latitude: `latitude`, `lat`, 1 (GeoJSON array)
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- elevation: `elevation`, `elev`, `alt`, `altitude`, 2 (GeoJSON array)
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<h4>Examples</h4>
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`geolib.latitude({lat: 51.49611, lng: 7.38896}); // -> 51.49611`
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`geolib.longitude({lat: 51.49611, lng: 7.38896}); // -> 7.38896`
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<h3>geolib.useDecimal(mixed latlng)</h3>
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Checks if a coordinate is already in decimal format and, if not, converts it to
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<h4>Example</h4>
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<pre>geolib.useDecimal("51° 29' 46\" N"); // -> 51.59611111
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geolib.useDecimal(51.59611111) // -> 51.59611111</pre>
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<h3>geolib.computeDestinationPoint(start, distance, bearing, radius(optional))</h3>
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Computes the destination point given an initial point, a distance and a bearing
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If no radius is given it defaults to the mean earth radius of 6371000 meter.
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Returns an object: `{"latitude": destLat, "longitude": destLng}`
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(Attention: this formula is not *100%* accurate (but very close though))
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<h4>Example</h4>
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<pre>var initialPoint = {lat: 51.516272, lon: 0.45425}
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var dist = 1234;
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var bearing = 45;
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geolib.computeDestinationPoint(initialPoint, dist, bearing);
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// -> {"latitude":51.52411853234181,"longitude":0.4668623365950795}
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</pre>
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<h2>Changelog</h2>
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<h3>v2.0.0+beta1</h3>
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- Dropped support for IE6, IE7, IE8
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- Added new methods `geolib.latitude()`, `geolib.longitude()`, `geolib.elevation()` to get latitude, longitude or elevation of points. Will be converted to decimal format automatically
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- Added new method `geolib.extend()` to extend geolib object
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- Added support for GeoJSON format (`[lon, lat, elev]`)
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- Added property `geolib.version` to query the currently used version
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- Moved `geolib.elevation` to an optional module (`geolib.elevation.js`)
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- Using `Object.create(Geolib.prototype)` instead of object literal `{}`
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- New folder structure: compiled `geolib.js` can now be found in `dist/` instead of root dir
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- Improved Grunt build task
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