我想开发一个使用cordova / phonegap的移动应用程序，它会找到行进的距离，平均而言。特定固定时间范围的速度和加速度表示20秒。由用户提供。
我已经读过可以在那里使用phonegap的地理定位或加速度计api，但我很困惑，无法理解使用哪个公式或方法以及如何计算这些值？
请帮助我实现此功能。
答案 0 :(得分：5)
this page底部的Javascript库对于使用lat / lon坐标非常有用。它允许您轻松计算点之间的距离，从而计算速度，加速度等。
然后，使用Phonegap地理位置API，您可以执行以下操作：
var currentUpdate, lastUpdate;
function onPositionUpdate(position){
if(currentUpdate) lastUpdate = currentUpdate;
currentUpdate = {
position: new LatLon(position.coords.latitude, position.coords.longitude),
time: new Date()
};
if(!lastUpdate) return;
currentUpdate.deltaDistMetres = lastUpdate.position.distanceTo(currentUpdate.position)*1000;
currentUpdate.deltaTimeSecs = (currentUpdate.time - lastUpdate.time)*1000;
currentUpdate.speed = (currentUpdate.deltaDistMetres/currentUpdate.deltaTimeSecs);
currentUpdate.accelerationGPS = (currentUpdate.speed - lastUpdate.speed) / currentUpdate.deltaTimeSecs;
console.log("Distance moved: "+currentUpdate.deltaDistMetres+" m; Avg speed: "+currentUpdate.speed+" m/s; Acceleration: "+currentUpdate.accelerationGPS + "m/s/s");
}
function onPositionError(error){
console.log("Error: "+error.message);
}
$(document).on("deviceready", function() {
navigator.geolocation.watchPosition(onPositionUpdate, onPositionError, {timeout: 30000, enableHighAccuracy: true});
});
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Latitude/longitude spherical geodesy formulae & scripts (c) Chris Veness 2002-2012 */
/* - www.movable-type.co.uk/scripts/latlong.html */
/* */
/* Sample usage: */
/* var p1 = new LatLon(51.5136, -0.0983); */
/* var p2 = new LatLon(51.4778, -0.0015); */
/* var dist = p1.distanceTo(p2); // in km */
/* var brng = p1.bearingTo(p2); // in degrees clockwise from north */
/* ... etc */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Note that minimal error checking is performed in this example code! */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/**
* Object LatLon: tools for geodetic calculations
*
* @requires Geo
*/
/**
* Creates a point on the earth's surface at the supplied latitude / longitude
*
* @constructor
* @param {Number} lat: latitude in degrees
* @param {Number} lon: longitude in degrees
* @param {Number} [radius=6371]: radius of earth if different value is required from standard 6,371km
*/
function LatLon(lat, lon, radius) {
if (typeof(radius) == 'undefined') radius = 6371; // earth's mean radius in km
this.lat = Number(lat);
this.lon = Number(lon);
this.radius = Number(radius);
}
/**
* Returns the distance from this point to the supplied point, in km
* (using Haversine formula)
*
* from: Haversine formula - R. W. Sinnott, "Virtues of the Haversine",
* Sky and Telescope, vol 68, no 2, 1984
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @param {Number} [precision=4]: number of significant digits to use for returned value
* @returns {Number} distance in km between this point and destination point
*/
LatLon.prototype.distanceTo = function(point, precision) {
// default 4 sig figs reflects typical 0.3% accuracy of spherical model
if (typeof precision == 'undefined') precision = 4;
var R = this.radius;
var φ1 = this.lat.toRadians(), λ1 = this.lon.toRadians();
var φ2 = point.lat.toRadians(), λ2 = point.lon.toRadians();
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;
return d.toPrecisionFixed(Number(precision));
}
/**
* Returns the (initial) bearing from this point to the supplied point, in degrees
* see http://williams.best.vwh.net/avform.htm#Crs
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {Number} initial bearing in degrees from North
*/
LatLon.prototype.bearingTo = function(point) {
var φ1 = this.lat.toRadians(), φ2 = point.lat.toRadians();
var Δλ = (point.lon-this.lon).toRadians();
var y = Math.sin(Δλ) * Math.cos(φ2);
var x = Math.cos(φ1)*Math.sin(φ2) -
Math.sin(φ1)*Math.cos(φ2)*Math.cos(Δλ);
var θ = Math.atan2(y, x);
return (θ.toDegrees()+360) % 360;
}
/**
* Returns final bearing arriving at supplied destination point from this point; the final bearing
* will differ from the initial bearing by varying degrees according to distance and latitude
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {Number} final bearing in degrees from North
*/
LatLon.prototype.finalBearingTo = function(point) {
// get initial bearing from supplied point back to this point...
var φ1 = point.lat.toRadians(), φ2 = this.lat.toRadians();
var Δλ = (this.lon-point.lon).toRadians();
var y = Math.sin(Δλ) * Math.cos(φ2);
var x = Math.cos(φ1)*Math.sin(φ2) -
Math.sin(φ1)*Math.cos(φ2)*Math.cos(Δλ);
var θ = Math.atan2(y, x);
// ... & reverse it by adding 180°
return (θ.toDegrees()+180) % 360;
}
/**
* Returns the midpoint between this point and the supplied point.
* see http://mathforum.org/library/drmath/view/51822.html for derivation
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {LatLon} midpoint between this point and the supplied point
*/
LatLon.prototype.midpointTo = function(point) {
var φ1 = this.lat.toRadians(), λ1 = this.lon.toRadians();
var φ2 = point.lat.toRadians();
var Δλ = (point.lon-this.lon).toRadians();
var Bx = Math.cos(φ2) * Math.cos(Δλ);
var By = Math.cos(φ2) * Math.sin(Δλ);
var φ3 = Math.atan2(Math.sin(φ1)+Math.sin(φ2),
Math.sqrt( (Math.cos(φ1)+Bx)*(Math.cos(φ1)+Bx) + By*By) );
var λ3 = λ1 + Math.atan2(By, Math.cos(φ1) + Bx);
λ3 = (λ3+3*Math.PI) % (2*Math.PI) - Math.PI; // normalise to -180..+180º
return new LatLon(φ3.toDegrees(), λ3.toDegrees());
}
/**
* Returns the destination point from this point having travelled the given distance (in km) on the
* given initial bearing (bearing may vary before destination is reached)
*
* see http://williams.best.vwh.net/avform.htm#LL
*
* @this {LatLon} latitude/longitude of origin point
* @param {Number} brng: initial bearing in degrees
* @param {Number} dist: distance in km
* @returns {LatLon} destination point
*/
LatLon.prototype.destinationPoint = function(brng, dist) {
var θ = Number(brng).toRadians();
var δ = Number(dist) / this.radius; // angular distance in radians
var φ1 = this.lat.toRadians();
var λ1 = this.lon.toRadians();
var φ2 = Math.asin( Math.sin(φ1)*Math.cos(δ) +
Math.cos(φ1)*Math.sin(δ)*Math.cos(θ) );
var λ2 = λ1 + Math.atan2(Math.sin(θ)*Math.sin(δ)*Math.cos(φ1),
Math.cos(δ)-Math.sin(φ1)*Math.sin(φ2));
λ2 = (λ2+3*Math.PI) % (2*Math.PI) - Math.PI; // normalise to -180..+180º
return new LatLon(φ2.toDegrees(), λ2.toDegrees());
}
/**
* Returns the point of intersection of two paths defined by point and bearing
*
* see http://williams.best.vwh.net/avform.htm#Intersection
*
* @param {LatLon} p1: first point
* @param {Number} brng1: initial bearing from first point
* @param {LatLon} p2: second point
* @param {Number} brng2: initial bearing from second point
* @returns {LatLon} destination point (null if no unique intersection defined)
*/
LatLon.intersection = function(p1, brng1, p2, brng2) {
var φ1 = p1.lat.toRadians(), λ1 = p1.lon.toRadians();
var φ2 = p2.lat.toRadians(), λ2 = p2.lon.toRadians();
var θ13 = Number(brng1).toRadians(), θ23 = Number(brng2).toRadians();
var Δφ = φ2-φ1, Δλ = λ2-λ1;
var δ12 = 2*Math.asin( Math.sqrt( Math.sin(Δφ/2)*Math.sin(Δφ/2) +
Math.cos(φ1)*Math.cos(φ2)*Math.sin(Δλ/2)*Math.sin(Δλ/2) ) );
if (δ12 == 0) return null;
// initial/final bearings between points
var θ1 = Math.acos( ( Math.sin(φ2) - Math.sin(φ1)*Math.cos(δ12) ) /
( Math.sin(δ12)*Math.cos(φ1) ) );
if (isNaN(θ1)) θ1 = 0; // protect against rounding
var θ2 = Math.acos( ( Math.sin(φ1) - Math.sin(φ2)*Math.cos(δ12) ) /
( Math.sin(δ12)*Math.cos(φ2) ) );
if (Math.sin(λ2-λ1) > 0) {
θ12 = θ1;
θ21 = 2*Math.PI - θ2;
} else {
θ12 = 2*Math.PI - θ1;
θ21 = θ2;
}
var α1 = (θ13 - θ12 + Math.PI) % (2*Math.PI) - Math.PI; // angle 2-1-3
var α2 = (θ21 - θ23 + Math.PI) % (2*Math.PI) - Math.PI; // angle 1-2-3
if (Math.sin(α1)==0 && Math.sin(α2)==0) return null; // infinite intersections
if (Math.sin(α1)*Math.sin(α2) < 0) return null; // ambiguous intersection
//α1 = Math.abs(α1);
//α2 = Math.abs(α2);
// ... Ed Williams takes abs of α1/α2, but seems to break calculation?
var α3 = Math.acos( -Math.cos(α1)*Math.cos(α2) +
Math.sin(α1)*Math.sin(α2)*Math.cos(δ12) );
var δ13 = Math.atan2( Math.sin(δ12)*Math.sin(α1)*Math.sin(α2),
Math.cos(α2)+Math.cos(α1)*Math.cos(α3) )
var φ3 = Math.asin( Math.sin(φ1)*Math.cos(δ13) +
Math.cos(φ1)*Math.sin(δ13)*Math.cos(θ13) );
var Δλ13 = Math.atan2( Math.sin(θ13)*Math.sin(δ13)*Math.cos(φ1),
Math.cos(δ13)-Math.sin(φ1)*Math.sin(φ3) );
var λ3 = λ1 + Δλ13;
λ3 = (λ3+3*Math.PI) % (2*Math.PI) - Math.PI; // normalise to -180..+180º
return new LatLon(φ3.toDegrees(), λ3.toDegrees());
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/**
* Returns the distance from this point to the supplied point, in km, travelling along a rhumb line
*
* see http://williams.best.vwh.net/avform.htm#Rhumb
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {Number} distance in km between this point and destination point
*/
LatLon.prototype.rhumbDistanceTo = function(point) {
var R = this.radius;
var φ1 = this.lat.toRadians(), φ2 = point.lat.toRadians();
var Δφ = φ2 - φ1;
var Δλ = Math.abs(point.lon-this.lon).toRadians();
// if dLon over 180° take shorter rhumb line across the anti-meridian:
if (Math.abs(Δλ) > Math.PI) Δλ = Δλ>0 ? -(2*Math.PI-Δλ) : (2*Math.PI+Δλ);
// on Mercator projection, longitude gets increasing stretched by latitude; q is the 'stretch factor'
var Δψ = Math.log(Math.tan(φ2/2+Math.PI/4)/Math.tan(φ1/2+Math.PI/4));
// the stretch factor becomes ill-conditioned along E-W line (0/0); use empirical tolerance to avoid it
var q = Math.abs(Δψ) > 10e-12 ? Δφ/Δψ : Math.cos(φ1);
// distance is pythagoras on 'stretched' Mercator projection
var δ = Math.sqrt(Δφ*Δφ + q*q*Δλ*Δλ); // angular distance in radians
var dist = δ * R;
return dist.toPrecisionFixed(4); // 4 sig figs reflects typical 0.3% accuracy of spherical model
}
/**
* Returns the bearing from this point to the supplied point along a rhumb line, in degrees
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {Number} bearing in degrees from North
*/
LatLon.prototype.rhumbBearingTo = function(point) {
var φ1 = this.lat.toRadians(), φ2 = point.lat.toRadians();
var Δλ = (point.lon-this.lon).toRadians();
// if dLon over 180° take shorter rhumb line across the anti-meridian:
if (Math.abs(Δλ) > Math.PI) Δλ = Δλ>0 ? -(2*Math.PI-Δλ) : (2*Math.PI+Δλ);
var Δψ = Math.log(Math.tan(φ2/2+Math.PI/4)/Math.tan(φ1/2+Math.PI/4));
var θ = Math.atan2(Δλ, Δψ);
return (θ.toDegrees()+360) % 360;
}
/**
* Returns the destination point from this point having travelled the given distance (in km) on the
* given bearing along a rhumb line
*
* @this {LatLon} latitude/longitude of origin point
* @param {Number} brng: bearing in degrees from North
* @param {Number} dist: distance in km
* @returns {LatLon} destination point
*/
LatLon.prototype.rhumbDestinationPoint = function(brng, dist) {
var δ = Number(dist) / this.radius; // angular distance in radians
var φ1 = this.lat.toRadians(), λ1 = this.lon.toRadians();
var θ = Number(brng).toRadians();
var Δφ = δ * Math.cos(θ);
var φ2 = φ1 + Δφ;
// check for some daft bugger going past the pole, normalise latitude if so
if (Math.abs(φ2) > Math.PI/2) φ2 = φ2>0 ? Math.PI-φ2 : -Math.PI-φ2;
var Δψ = Math.log(Math.tan(φ2/2+Math.PI/4)/Math.tan(φ1/2+Math.PI/4));
var q = Math.abs(Δψ) > 10e-12 ? Δφ / Δψ : Math.cos(φ1); // E-W course becomes ill-conditioned with 0/0
var Δλ = δ*Math.sin(θ)/q;
var λ2 = λ1 + Δλ;
λ2 = (λ2 + 3*Math.PI) % (2*Math.PI) - Math.PI; // normalise to -180..+180º
return new LatLon(φ2.toDegrees(), λ2.toDegrees());
}
/**
* Returns the loxodromic midpoint (along a rhumb line) between this point and the supplied point.
* see http://mathforum.org/kb/message.jspa?messageID=148837
*
* @this {LatLon} latitude/longitude of origin point
* @param {LatLon} point: latitude/longitude of destination point
* @returns {LatLon} midpoint between this point and the supplied point
*/
LatLon.prototype.rhumbMidpointTo = function(point) {
var φ1 = this.lat.toRadians(), λ1 = this.lon.toRadians();
var φ2 = point.lat.toRadians(), λ2 = point.lon.toRadians();
if (Math.abs(λ2-λ1) > Math.PI) λ1 += 2*Math.PI; // crossing anti-meridian
var φ3 = (φ1+φ2)/2;
var f1 = Math.tan(Math.PI/4 + φ1/2);
var f2 = Math.tan(Math.PI/4 + φ2/2);
var f3 = Math.tan(Math.PI/4 + φ3/2);
var λ3 = ( (λ2-λ1)*Math.log(f3) + λ1*Math.log(f2) - λ2*Math.log(f1) ) / Math.log(f2/f1);
if (!isFinite(λ3)) λ3 = (λ1+λ2)/2; // parallel of latitude
λ3 = (λ3 + 3*Math.PI) % (2*Math.PI) - Math.PI; // normalise to -180..+180º
return new LatLon(φ3.toDegrees(), λ3.toDegrees());
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/**
* Returns a string representation of this point; format and dp as per lat()/lon()
*
* @this {LatLon} latitude/longitude of origin point
* @param {String} [format]: return value as 'd', 'dm', 'dms'
* @param {Number} [dp=0|2|4]: number of decimal places to display
* @returns {String} comma-separated latitude/longitude
*/
LatLon.prototype.toString = function(format, dp) {
if (typeof format == 'undefined') format = 'dms';
return Geo.toLat(this.lat, format, dp) + ', ' + Geo.toLon(this.lon, format, dp);
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
// ---- extend Number object with methods for converting degrees/radians
/** Converts numeric degrees to radians */
if (typeof Number.prototype.toRadians == 'undefined') {
Number.prototype.toRadians = function() {
return this * Math.PI / 180;
}
}
/** Converts radians to numeric (signed) degrees */
if (typeof Number.prototype.toDegrees == 'undefined') {
Number.prototype.toDegrees = function() {
return this * 180 / Math.PI;
}
}
/**
* Formats the significant digits of a number, using only fixed-point notation (no exponential)
*
* @param {Number} precision: Number of significant digits to appear in the returned string
* @returns {String} A string representation of number which contains precision significant digits
*/
if (typeof Number.prototype.toPrecisionFixed == 'undefined') {
Number.prototype.toPrecisionFixed = function(precision) {
// use standard toPrecision method
var n = this.toPrecision(precision);
// ... but replace +ve exponential format with trailing zeros
n = n.replace(/(.+)e\+(.+)/, function(n, sig, exp) {
sig = sig.replace(/\./, ''); // remove decimal from significand
l = sig.length - 1;
while (exp-- > l) sig = sig + '0'; // append zeros from exponent
return sig;
});
// ... and replace -ve exponential format with leading zeros
n = n.replace(/(.+)e-(.+)/, function(n, sig, exp) {
sig = sig.replace(/\./, ''); // remove decimal from significand
while (exp-- > 1) sig = '0' + sig; // prepend zeros from exponent
return '0.' + sig;
});
return n;
}
}
/** Trims whitespace from string (q.v. blog.stevenlevithan.com/archives/faster-trim-javascript) */
if (typeof String.prototype.trim == 'undefined') {
String.prototype.trim = function() {
return String(this).replace(/^\s\s*/, '').replace(/\s\s*$/, '');
}
}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
if (!window.console) window.console = { log: function() {} };
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
/* Geodesy representation conversion functions (c) Chris Veness 2002-2012 */
/* - www.movable-type.co.uk/scripts/latlong.html */
/* */
/* Sample usage: */
/* var lat = Geo.parseDMS('51° 28′ 40.12″ N'); */
/* var lon = Geo.parseDMS('000° 00′ 05.31″ W'); */
/* var p1 = new LatLon(lat, lon); */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
var Geo = {}; // Geo namespace, representing static class
/**
* Parses string representing degrees/minutes/seconds into numeric degrees
*
* This is very flexible on formats, allowing signed decimal degrees, or deg-min-sec optionally
* suffixed by compass direction (NSEW). A variety of separators are accepted (eg 3º 37' 09"W)
* or fixed-width format without separators (eg 0033709W). Seconds and minutes may be omitted.
* (Note minimal validation is done).
*
* @param {String|Number} dmsStr: Degrees or deg/min/sec in variety of formats
* @returns {Number} Degrees as decimal number
* @throws {TypeError} dmsStr is an object, perhaps DOM object without .value?
*/
Geo.parseDMS = function(dmsStr) {
if (typeof deg == 'object') throw new TypeError('Geo.parseDMS - dmsStr is [DOM?] object');
// check for signed decimal degrees without NSEW, if so return it directly
if (typeof dmsStr === 'number' && isFinite(dmsStr)) return Number(dmsStr);
// strip off any sign or compass dir'n & split out separate d/m/s
var dms = String(dmsStr).trim().replace(/^-/,'').replace(/[NSEW]$/i,'').split(/[^0-9.,]+/);
if (dms[dms.length-1]=='') dms.splice(dms.length-1); // from trailing symbol
if (dms == '') return NaN;
// and convert to decimal degrees...
switch (dms.length) {
case 3: // interpret 3-part result as d/m/s
var deg = dms[0]/1 + dms[1]/60 + dms[2]/3600;
break;
case 2: // interpret 2-part result as d/m
var deg = dms[0]/1 + dms[1]/60;
break;
case 1: // just d (possibly decimal) or non-separated dddmmss
var deg = dms[0];
// check for fixed-width unseparated format eg 0033709W
//if (/[NS]/i.test(dmsStr)) deg = '0' + deg; // - normalise N/S to 3-digit degrees
//if (/[0-9]{7}/.test(deg)) deg = deg.slice(0,3)/1 + deg.slice(3,5)/60 + deg.slice(5)/3600;
break;
default:
return NaN;
}
if (/^-|[WS]$/i.test(dmsStr.trim())) deg = -deg; // take '-', west and south as -ve
return Number(deg);
}
/**
* Convert decimal degrees to deg/min/sec format
* - degree, prime, double-prime symbols are added, but sign is discarded, though no compass
* direction is added
*
* @private
* @param {Number} deg: Degrees
* @param {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @returns {String} deg formatted as deg/min/secs according to specified format
* @throws {TypeError} deg is an object, perhaps DOM object without .value?
*/
Geo.toDMS = function(deg, format, dp) {
if (typeof deg == 'object') throw new TypeError('Geo.toDMS - deg is [DOM?] object');
if (isNaN(deg)) return null; // give up here if we can't make a number from deg
// default values
if (typeof format == 'undefined') format = 'dms';
if (typeof dp == 'undefined') {
switch (format) {
case 'd': dp = 4; break;
case 'dm': dp = 2; break;
case 'dms': dp = 0; break;
default: format = 'dms'; dp = 0; // be forgiving on invalid format
}
}
deg = Math.abs(deg); // (unsigned result ready for appending compass dir'n)
switch (format) {
case 'd':
d = deg.toFixed(dp); // round degrees
if (d<100) d = '0' + d; // pad with leading zeros
if (d<10) d = '0' + d;
dms = d + '\u00B0'; // add º symbol
break;
case 'dm':
var min = (deg*60).toFixed(dp); // convert degrees to minutes & round
var d = Math.floor(min / 60); // get component deg/min
var m = (min % 60).toFixed(dp); // pad with trailing zeros
if (d<100) d = '0' + d; // pad with leading zeros
if (d<10) d = '0' + d;
if (m<10) m = '0' + m;
dms = d + '\u00B0' + m + '\u2032'; // add º, ' symbols
break;
case 'dms':
var sec = (deg*3600).toFixed(dp); // convert degrees to seconds & round
var d = Math.floor(sec / 3600); // get component deg/min/sec
var m = Math.floor(sec/60) % 60;
var s = (sec % 60).toFixed(dp); // pad with trailing zeros
if (d<100) d = '0' + d; // pad with leading zeros
if (d<10) d = '0' + d;
if (m<10) m = '0' + m;
if (s<10) s = '0' + s;
dms = d + '\u00B0' + m + '\u2032' + s + '\u2033'; // add º, ', " symbols
break;
}
return dms;
}
/**
* Convert numeric degrees to deg/min/sec latitude (suffixed with N/S)
*
* @param {Number} deg: Degrees
* @param {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @returns {String} Deg/min/seconds
*/
Geo.toLat = function(deg, format, dp) {
var lat = Geo.toDMS(deg, format, dp);
return lat==null ? '–' : lat.slice(1) + (deg<0 ? 'S' : 'N'); // knock off initial '0' for lat!
}
/**
* Convert numeric degrees to deg/min/sec longitude (suffixed with E/W)
*
* @param {Number} deg: Degrees
* @param {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @returns {String} Deg/min/seconds
*/
Geo.toLon = function(deg, format, dp) {
var lon = Geo.toDMS(deg, format, dp);
return lon==null ? '–' : lon + (deg<0 ? 'W' : 'E');
}
/**
* Convert numeric degrees to deg/min/sec as a bearing (0º..360º)
*
* @param {Number} deg: Degrees
* @param {String} [format=dms]: Return value as 'd', 'dm', 'dms'
* @param {Number} [dp=0|2|4]: No of decimal places to use - default 0 for dms, 2 for dm, 4 for d
* @returns {String} Deg/min/seconds
*/
Geo.toBrng = function(deg, format, dp) {
deg = (Number(deg)+360) % 360; // normalise -ve values to 180º..360º
var brng = Geo.toDMS(deg, format, dp);
return brng==null ? '–' : brng.replace('360', '0'); // just in case rounding took us up to 360º!
}
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