I have data of associates with their Longitudes and Latitudes. I want to detect the nearest associate to the User Location. user location i will detect with the Android SDK.
My Question how to match the params in such a way that APP can show the best nearest associates. thanks in Advance.
Considering your list of associates is non-null array of lats longs.
LatLng GetNearest(LatLng myPos, LatLng[] Associates)
{
double nearestDistance = distance(myPos.lat, myPos.lng, Associates[0].lat,Associates[0].lng);
LatLng Nearest = Associates[0];
for(int i = 1; i < Associates.length(); i ++)
{
double _d = distance(myPos.lat, myPos.lng, Associates[i].lat, Associates[i].lng);
if(_d < nearestDistance)
{
nearestDistance = _d;
Nearest = Associates[i];
}
}
return Nearest;
}
/** calculates the distance between two locations in MILES */
private double distance(double lat1, double lng1, double lat2, double lng2) {
double earthRadius = 3958.75; // in miles, change to 6371 for kilometer output
double dLat = Math.toRadians(lat2-lat1);
double dLng = Math.toRadians(lng2-lng1);
double sindLat = Math.sin(dLat / 2);
double sindLng = Math.sin(dLng / 2);
double a = Math.pow(sindLat, 2) + Math.pow(sindLng, 2)
* Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2));
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
double dist = earthRadius * c;
return dist; // output distance, in MILES
}
I assume you have a POJO of Associates, in which you have Longitudes and Latitudes for each of your associate, So let's say you have an Array of associates then to find the nearest to user location, use this short and simple logic :
for (Associates associate : associates) {
Double associateLatitude = associate.getLatitude();
Double associateLongitude = associate.getLongitude();
android.location.Location locationOne = new android.location.Location("");
locationOne.setLatitude(userLatitude);
locationOne.setLongitude(userLongitude);
android.location.Location locationTwo = new android.location.Location("");
locationTwo.setLongitude(associateLongitude);
locationTwo.setLatitude(associateLatitude);
float distance = locationOne.distanceTo(locationTwo);
if (disTemp == 0.0f) {
disTemp = distance;
nearestAssociate = associate;
} else if (disTemp > distance) {
disTemp = distance;
nearestAssociate = associate;
}
}
Related
Till now, I have inserted all the sets of latitude and longitude in my database after every 5 sec from the path I have travelled.
Now after reaching the destination I have to calculate the distance from the sets of Latitude, longitude. It's not about calculating the travelling distance between two points but to get the total distance travelled from set of lat,long in my database .
I have thought a way of calculating the total distance by getting the distance between the two points
and add them up at last
Is there any better solution than this? please suggest and help
Already read this SO post but not getting how I will get the total distance by using the Google Maps Distance Matrix API
///////service to insert coordinates into the database.
private class MyReceiver extends BroadcastReceiver {
#Override
public void onReceive(Context arg0, Intent arg1) {
String name = arg1.getAction();
if (name.equalsIgnoreCase("Location_Changed")) {
db.insertlatlong(new Latilongi(arg1.getStringExtra("latitude"),
arg1.getStringExtra("longitude"),currentDateandTime));
} else if (arg1.getAction().matches("android.location.PROVIDERS_CHANGED")) {
Toast.makeText(MapActivity.this, "in android.location.PROVIDERS_CHANGED",
Toast.LENGTH_SHORT).show();
}
}
}
you can use the following method that will give you acurate result
public double CalculationByDistance(LatLng StartP, LatLng EndP) {
int Radius = 6371;// radius of earth in Km
double lat1 = StartP.latitude;
double lat2 = EndP.latitude;
double lon1 = StartP.longitude;
double lon2 = EndP.longitude;
double dLat = Math.toRadians(lat2 - lat1);
double dLon = Math.toRadians(lon2 - lon1);
double a = Math.sin(dLat / 2) * Math.sin(dLat / 2)
+ Math.cos(Math.toRadians(lat1))
* Math.cos(Math.toRadians(lat2)) * Math.sin(dLon / 2)
* Math.sin(dLon / 2);
double c = 2 * Math.asin(Math.sqrt(a));
double valueResult = Radius * c;
double km = valueResult / 1;
DecimalFormat newFormat = new DecimalFormat("####");
int kmInDec = Integer.valueOf(newFormat.format(km));
double meter = valueResult % 1000;
int meterInDec = Integer.valueOf(newFormat.format(meter));
Log.i("Radius Value", "" + valueResult + " KM " + kmInDec
+ " Meter " + meterInDec);
return Radius * c;
}
try this one
private double distance(double lat1, double lon1, double lat2, double lon2, String unit) {
double theta = lon1 - lon2;
double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2)) + Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.cos(deg2rad(theta));
dist = Math.acos(dist);
dist = rad2deg(dist);
dist = dist * 60 * 1.1515;
if (unit == "K") {
dist = dist * 1.609344;
} else if (unit == "N") {
dist = dist * 0.8684;
}
return (dist);
}
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
/*:: This function converts decimal degrees to radians :*/
/*:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::*/
private static double deg2rad(double deg) {
return (deg * Math.PI / 180.0);
}
You can insert only distance between two co-ordinates and lastly sum up all distances you had in database. Distance achieve like below.
float distanceInMeters = lastLocation.distanceTo(myLocation);
where "lastLocation" and "myLocation" are of Location object.
If you dont have Location object than you can try this.
Location lastLocation = new Location("");
lastLocation.setLatitude(latitude);
lastLocation.setLongitude(longitude);
Location myLocation = new Location("");
myLocation.setLatitude(otherlatitude);
myLocation.setLongitude(otherlongitude);
float distanceInMeters = lastLocation.distanceTo(myLocation);
I have a list of latitude and longitude stored in database. Now I'm trying to develop a function on finding nearby place from my current location. Means that, i have to search all the latitude and longitude from my database and see which of the places are within my area will be shown.
Location.distanceBetween(lat1,lon1, lat2,lon2, result);
To find the distance from one two-dimensional point to another you can use the Haversine formula, (without calling any API functions.)
// All measurements are in meters
var rad = function(x) {
return x * Math.PI / 180;
};
var getDistance = function(coord1, coord2) {
// This is the Earth's radius
var earthRad = 6378137;
var dLat = rad(coord2.lat() - coord1.lat());
var dLong = rad(coord2.lng() - coord1.lng());
var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(rad(coord1.lat())) * Math.cos(rad(coord2.lat())) *
Math.sin(dLong / 2) * Math.sin(dLong / 2);
var b = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
var distance = earthRad * b;
// Returns distance from coord1 to coord2 in meters
return distance;
};
Your question is a bit broad so this might not be the best solution. If you were constantly updating your current location you'd have to implement a Tree Sorting algorithm or some other way of optimizing performance rather than checking through your database for distances on every update.
You can use the Location object. The distanceBetween or distanceTo method will give you the 'as the crow flies' distance between two points. From there you can filter your results and display only the places you want to.
here is what i use
public void nearBy() {
if (map.getMyLocation() != null) {//check if my location was found
db = new MyDatabase(MainActivity.context);
Cursor medecin = db.lireMedecin();//read values from database
map.clear();//clearing the map
while (medecin.getPosition() < medecin.getCount()) { //cheking if this doctor is nearby...
String Lat1 = medecin.getString(5);//doctor's latitude
String Lon1 = medecin.getString(6);//doctor's longitude
LatLng me = new LatLng(map.getMyLocation().getLatitude(), map.getMyLocation().getLongitude());//my location
LatLng med = new LatLng(Double.parseDouble(Lat1), Double.parseDouble(Lon1));//doctor location
if (CalDist(me, med) < 6) {//if distance is < 6km add marker to the map
map.addMarker(new MarkerOptions().position(med).title(medecin.getString(1) + " " + medecin.getString(2))
.snippet(medecin.getString(4)).icon(BitmapDescriptorFactory
.fromResource(Icone(medecin.getString(7).charAt(0))))); //showing the doctor on the map
}
medecin.moveToNext();//next doctor
}
} else
Toast.makeText(context, "Gps signal not valid", Toast.LENGTH_SHORT).show();//can't find my position
}
calculate distance :
public static double CalDist(LatLng StartP, LatLng EndP) {
int Radius = 6371;//radius of earth in Km
double lat1 = StartP.latitude ;
double lat2 = EndP.latitude ;
double lon1 = StartP.longitude ;
double lon2 = EndP.longitude ;
double dLat = Math.toRadians(lat2 - lat1);
double dLon = Math.toRadians(lon2 - lon1);
double a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(Math.toRadians(lat1)) * Math.cos(Math.toRadians(lat2)) *
Math.sin(dLon / 2) * Math.sin(dLon / 2);
double c = 2 * Math.asin(Math.sqrt(a));
return Radius * c;
}
I have a DB with Geopoints.
I need to do a query to get all geopoints in the radius of X meters of me.
How can i do this?
I think the best way is get the minimal lat/long possible point, and the max lat/long point and get all of them for which: geopoint > minPoint AND geopoint < MaxPoint
Other ideas?
You can use this class to get de distance between to points:
How to use:
double distInKm = GeoMath.getDistance(12.345, -8.788, 12.33, -8.77);
Or, if point1 and point2 are GeoPoint:
double distInKm = GeoMath.getDistance(point1, point2);
You can also calculate a Geopoint that is a distance of you and along a bearing.
This computes a point that is 5 km northward from point1:
GeoPoint northPointAt5 = GeoMath.getGeoPointAlongBearing(point1, 0, 5);
You can calculate the other points at 90 degrees, 180 degrees and 270 degrees to calculate minPoint AND MaxPoint.
GeoMath class:
public class GeoMath {
public static final int EARTH_MEAN_RADIUS = 6371; // earth's mean radius in Km
public static double getDistance(double startLatitude, double startLongitude,
double endLatitude, double endLongitude){
return distHaversine(startLatitude,startLongitude,endLatitude,endLongitude);
}
public static double getDistance(GeoPoint point1, GeoPoint point2){
return distHaversine(point1.getLatitudeE6()/1E6, point1.getLongitudeE6()/1E6,
point2.getLatitudeE6()/1E6, point2.getLongitudeE6()/1E6);
}
private static double getSpanInRadians(double max, double min){
return Math.toRadians(max - min);
}
//Distance in Km between point1 (lat1,lon1) and point2 (lat2,lon2) Haversine formula
private static double distHaversine(double lat1, double lon1, double lat2, double lon2) {
double dLat = getSpanInRadians(lat2,lat1);
double dLon = getSpanInRadians(lon2,lon1);
lat1 = Math.toRadians(lat1);
lat2 = Math.toRadians(lat2);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.cos(lat1) * Math.cos(lat2) * Math.sin(dLon/2) * Math.sin(dLon/2);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
double dist = EARTH_MEAN_RADIUS * c;
return Math.round(dist * 1000)/1000; //3 decimal places
}
// Get GeoPoint at distance along a bearing
// bearing in degrees
// distance in Km
public static GeoPoint getGeoPointAlongBearing(GeoPoint location, double bearing, double distance){
double PI = Math.PI;
double NM = 1.852; //1 nm = 1.852 Km -> nm = Km/NM
GeoPoint geoPointAlongBearing;
double locationLatRad = Math.toRadians(location.getLatitudeE6()/1E6);
double locationLongRad = Math.toRadians(location.getLongitudeE6()/1E6)*(-1.0d);
double distanceRad = distance/NM * PI/(180*60);
double bearingRad = Math.toRadians(bearing);
double latAlongBearingRad = Math.asin(Math.sin(locationLatRad) *
Math.cos(distanceRad) +
Math.cos(locationLatRad) *
Math.sin(distanceRad) *
Math.cos(bearingRad));
double lonAlongBearingRad = mod(locationLongRad -
Math.asin(Math.sin(bearingRad) *
Math.sin(distanceRad) /
Math.cos(latAlongBearingRad)) + PI, 2 * PI) - PI;
double latAlongBearing = rad2lat(latAlongBearingRad);
double lonAlongBearing = rad2lng(lonAlongBearingRad) * (-1);
geoPointAlongBearing = new GeoPoint((int)(latAlongBearing*1E6),(int)(lonAlongBearing*1E6));
return geoPointAlongBearing;
}
private static double mod(double y, double x) {
return y - x * Math.floor(y/x);
}
}
With your query I think that you will find all points inside a square centered at your location and with a side length X.
After that, yuo can get all the points that are inside a circle centered at your location with radius X.
What about this pseudo code:
//create your location
Location yourLocation=new Location("myLoc");
double latitude = geoPointYourLocation.getLatitudeE6() / 1E6;
double longitude = geoPointYourLocation.getLongitudeE6() / 1E6;
yourLocation.setLatitude(latitude);
yourLocation.setLongitude(longitude);
//Browse geopoints from DB, convert to GeoPoint and check if it is at a distance less than X
for (geoPointTemp in in query geopoint of your DDBB inside square) {
//create the location of the geopoint
Location locTemp=new Location("locTemp");
double latitude = geoPointTemp.getLatitudeE6() / 1E6;
double longitude = geoPointTemp.getLongitudeE6() / 1E6;
locTemp.setLatitude(latitude);
locTemp.setLongitude(longitude);
//calculate the distance between you and de temporary location
double distance=yourLocation.distanceTo(locTemp);
if(distance<X){
//do something
}
With Mysql, you can use built-in spacial functions such as GLength, linestring ....
I'm not really good with mathematics but I need to calculate the distance of two different locations of the markers. Something like this:
public double CalculationByDistance(double initialLat, double initialLong, double finalLat, double finalLong){
return distance;
}
Or is there any alternative ways that I can calculate the distance of two markers, also I tried to google for answers.. but couldn't find any.
Reference:
http://en.wikipedia.org/wiki/Haversine_formula
Comments are appreciated :) Thanks!!
Try this, much simpler than Haversine!
Location me = new Location("");
Location dest = new Location("");
me.setLatitude(myLat);
me.setLongitude(myLong);
dest.setLatitude(destLat);
dest.setLongitude(destLong);
float dist = me.distanceTo(dest);
If you want to stick with Haversine, something like this:
public double CalculationByDistance(double initialLat, double initialLong,
double finalLat, double finalLong){
int R = 6371; // km (Earth radius)
double dLat = toRadians(finalLat-initialLat);
double dLon = toRadians(finalLong-initialLong);
initialLat = toRadians(initialLat);
finalLat = toRadians(finalLat);
double a = Math.sin(dLat/2) * Math.sin(dLat/2) +
Math.sin(dLon/2) * Math.sin(dLon/2) * Math.cos(initialLat) * Math.cos(finalLat);
double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
return R * c;
}
public double toRadians(double deg) {
return deg * (Math.PI/180);
}
Also, you need to create a method toRadians() that convert values from degrees to radians, which is quite easy.
Hope it helps!
From your wikipedia link, applying the formula directly you can do the following:
public double CalculationByDistance(double initialLat, double initialLong, double finalLat, double finalLong){
/*PRE: All the input values are in radians!*/
double latDiff = finalLat - initialLat;
double longDiff = finalLong - initialLong;
double earthRadius = 6371; //In Km if you want the distance in km
double distance = 2*earthRadius*Math.asin(Math.sqrt(Math.pow(Math.sin(latDiff/2.0),2)+Math.cos(initialLat)*Math.cos(finalLat)*Math.pow(Math.sin(longDiff/2),2)));
return distance;
}
Use the below method for calculating the distance of two different locations.
public double getKilometers(double lat1, double long1, double lat2, double long2) {
double PI_RAD = Math.PI / 180.0;
double phi1 = lat1 * PI_RAD;
double phi2 = lat2 * PI_RAD;
double lam1 = long1 * PI_RAD;
double lam2 = long2 * PI_RAD;
return 6371.01 * acos(sin(phi1) * sin(phi2) + cos(phi1) * cos(phi2) * cos(lam2 - lam1));
}
try this
/**
* This is the implementation Haversine Distance Algorithm between two places
* #author ananth
* R = earth’s radius (mean radius = 6,371km)
Δlat = lat2− lat1
Δlong = long2− long1
a = sin²(Δlat/2) + cos(lat1).cos(lat2).sin²(Δlong/2)
c = 2.atan2(√a, √(1−a))
d = R.c
*
*/
public class HaversineDistance {
/**
* #param args
* arg 1- latitude 1
* arg 2 — latitude 2
* arg 3 — longitude 1
* arg 4 — longitude 2
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
final int R = 6371; // Radious of the earth
Double lat1 = Double.parseDouble(args[0]);
Double lon1 = Double.parseDouble(args[1]);
Double lat2 = Double.parseDouble(args[2]);
Double lon2 = Double.parseDouble(args[3]);
Double latDistance = toRad(lat2-lat1);
Double lonDistance = toRad(lon2-lon1);
Double a = Math.sin(latDistance / 2) * Math.sin(latDistance / 2) +
Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) *
Math.sin(lonDistance / 2) * Math.sin(lonDistance / 2);
Double c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
Double distance = R * c;
System.out.println(“The distance between two lat and long is::” + distance);
}
private static Double toRad(Double value) {
return value * Math.PI / 180;
}
}
double distance;
Location locationA = new Location("point A");
locationA.setLatitude(latA);
locationA.setLongitude(lngA);
Location locationB = new Location("point B");
locationB.setLatitude(latB);
LocationB.setLongitude(lngB);
distance = locationA.distanceTo(locationB);
the above code is not working and i am getting 0.0 Km as distance?
Also in the constructor of the location class, what does the string provider mean.
In the above code i am using PointA and PointB as the providers.
why is the above code not working?
thank you in advance.
LOGCAT
05-09 17:48:56.144: INFO/current loc(1573): lat 0.0 lng 0.0
05-09 17:48:56.155: INFO/checklocation loc(1573): lat 54.4288665 lng 10.169366
Just a quick snippet since I didn't see a complete and simple solution with GeoPoints above:
public float getDistanceInMiles(GeoPoint p1, GeoPoint p2) {
double lat1 = ((double)p1.getLatitudeE6()) / 1e6;
double lng1 = ((double)p1.getLongitudeE6()) / 1e6;
double lat2 = ((double)p2.getLatitudeE6()) / 1e6;
double lng2 = ((double)p2.getLongitudeE6()) / 1e6;
float [] dist = new float[1];
Location.distanceBetween(lat1, lng1, lat2, lng2, dist);
return dist[0] * 0.000621371192f;
}
If you want meters, just return dist[0] directly.
Try Location.distanceBetween(..)
Update:
If you are getting lat/lon from GeoPoint then they are in microdegrees. You must multiply by 1e6.
As stated above, the Location Class is the way to go. Here is the code I have used :
Location locationA = new Location("point A");
locationA.setLatitude(pointA.getLatitudeE6() / 1E6);
locationA.setLongitude(pointA.getLongitudeE6() / 1E6);
Location locationB = new Location("point B");
locationB.setLatitude(pointB.getLatitudeE6() / 1E6);
locationB.setLongitude(pointB.getLongitudeE6() / 1E6);
double distance = locationA.distanceTo(locationB);
In this example, both pointA and pointB are instances of the GeoPoint class.
This is not an answer, but note the signature for the Location constructor is Location(String provider).
i.e. the String you pass to the constructor should be one of LocationManager.GPS_PROVIDER, LocationManager.NETWORK_PROVIDER or LocationManager.PASSIVE_PROVIDER, not "point A" and "point B".
An alternative way to accomplish the above,
public class Distance {
public static double distance(double lat1, double lon1, double lat2, double lon2) {
double theta = lon1 - lon2;
double dist = Math.sin(deg2rad(lat1)) * Math.sin(deg2rad(lat2))
+ Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2))
* Math.cos(deg2rad(theta));
dist = Math.acos(dist);
dist = rad2deg(dist);
dist = dist * 60 * 1.1515;
//if (unit == "K") {
// dist = dist * 1.609344;
// else if (unit == "N") {
//dist = dist * 0.8684;
//}
return (dist);
}
public static final double PI = 3.14159265;
public static final double deg2radians = PI/180.0;
public static double getDistance(double latitude1, double longitude1, double latitude2,double longitude2) {
double lat1 = latitude1 * deg2radians;
double lat2 = latitude2 * deg2radians;
double lon1 = longitude1 * deg2radians;
double lon2 = longitude2 * deg2radians;
// Williams gives two formulae;
// this is the more accurate for close distances.
// In practice, the two differed only in the 8th or 9th place, for
// separations as small as 1 degree.
double radd = 2 * Math.asin(Math.sqrt(Math.pow(Math.sin((lat1 - lat2) / 2),
2.0)
+ Math.cos(lat1)
* Math.cos(lat2)
* Math.pow(Math.sin((lon1 - lon2) / 2), 2.0)));
return radd;
}
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts decimal degrees to radians : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double deg2rad(double deg) {
return (deg * Math.PI / 180.0);
}
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
/* :: This function converts radians to decimal degrees : */
/* ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: */
private static double rad2deg(double rad) {
return (rad * 180.0 / Math.PI);
}
}
double CalculateDistance( double nLat1, double nLon1, double nLat2, double nLon2 )
{
double nRadius = 6371; // Earth's radius in Kilometers
// Get the difference between our two points
// then convert the difference into radians
double nDLat = ToRad(nLat2 - nLat1);
double nDLon = ToRad(nLon2 - nLon1);
// Here is the new line
nLat1 = ToRad(nLat1);
nLat2 = ToRad(nLat2);
double nA = pow ( sin(nDLat/2), 2 ) + cos(nLat1) * cos(nLat2) * pow ( sin(nDLon/2), 2 );
double nC = 2 * atan2( sqrt(nA), sqrt( 1 - nA ));
double nD = nRadius * nC;
return nD; // Return our calculated distance
}
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