Sort list of points lon \ lat, start from nearest

Question

I have a location from GPS (lon_base, lat_base). I have a list of places (lon1, lat1 | lon2, lat2 | lon3, lat3 ...) This list is very long and around the world.

My questions: 1. How to get from this list only lon \ lat, which are 1 mile from my lon_base \ lat_base? 2. How to sort them from the nearest to the farthest?

Thanks in advance!

Answer 1

You want to define your own Comparator, which, in general, looks something like this:

LonLat myHouse = /* whatever */ ;
Comparable comp = new Comparable () {
    LonLat a;
    int compareTo (Object b) {
        int aDist = calcDistance(a, myHouse) ;
        int bDist = calcDistance(b, myHouse) ;
        return aDist - bDist;
    }
};
myLonLatList.sort(lonLatList, comp);

calcDistance() . Android, , Google Maps - API, .

EDIT: , calcDistance() ChrisJ distance.

-tjw

Answer 2

public static List<Location> sortLocations(List<Location> locations, final double myLatitude,final double myLongitude) {
    Comparator comp = new Comparator<Location>() {
        @Override
        public int compare(Location o, Location o2) {
            float[] result1 = new float[3];
            android.location.Location.distanceBetween(myLatitude, myLongitude, o.Lat, o.Long, result1);
            Float distance1 = result1[0];

            float[] result2 = new float[3];
            android.location.Location.distanceBetween(myLatitude, myLongitude, o2.Lat, o2.Long, result2);
            Float distance2 = result2[0];

            return distance1.compareTo(distance2);
        }
    };


    Collections.sort(locations, comp);
    return locations;
}

, , , android.location.Location.

Answer 3

, , . formulae :

static double distance(double fromLat, double fromLon, double toLat, double toLon) {
    double radius = 6378137;   // approximate Earth radius, *in meters*
    double deltaLat = toLat - fromLat;
    double deltaLon = toLon - fromLon;
    double angle = 2 * Math.asin( Math.sqrt(
        Math.pow(Math.sin(deltaLat/2), 2) + 
        Math.cos(fromLat) * Math.cos(toLat) * 
        Math.pow(Math.sin(deltaLon/2), 2) ) );
    return radius * angle;
}

Answer 4

( 1 ), :

dx = cos(phi_base) * (theta - theta_base)
dy = phi - phi_base

dist = sqrt(dx*dx+dy*dy) 

: phi= theta=

60 , theta phi . , , , , , 1 .

phi_base ( pi/180), cos().

(: , 180 ° -180 °, , , :-)

.

(, , 2000 ), Great Circle Distance, .

Answer 5

In accordance with this link, I made a working method. The answer above was incorrect because it does not convert lat / lng degrees to radians.

    private double getDistance(double fromLat, double fromLon, double toLat, double toLon){
        double radius = 6371;   // Earth radius in km
        double deltaLat = Math.toRadians(toLat - fromLat);
        double deltaLon = Math.toRadians(toLon - fromLon);
        double lat1 = Math.toRadians(fromLat);
        double lat2 = Math.toRadians(toLat);
        double aVal = Math.sin(deltaLat/2) * Math.sin(deltaLat/2) +
            Math.sin(deltaLon/2) * Math.sin(deltaLon/2) * Math.cos(lat1) * Math.cos(lat2);
        double cVal = 2*Math.atan2(Math.sqrt(aVal), Math.sqrt(1-aVal));  

        double distance = radius*cVal;
        Log.d("distance","radius * angle = " +distance);
        return distance;
    }