Elasticsearch: Painless GeoPoint arcDistance

[bport]

It will be really confortable to allow call to arcDistance from GeoPoint. Indeed actually we can only call them from GeoPoints (and that will use only the first point).

[yeikel]

@bport Can you please add more information/background to the topic? I can't quite participate in the conversation with the limited information that you are providing.

[bport]

@yeikel In a sorting script I need to use the arcdistance for each location in a GeoPoints list.
However even if I can iterate this list I can use arcDistance on each GeoPoint because arcDistance is a GeoPoints method. And the implementation return the arcDistance for the 1st point.
So in order to allow script to get arcDistance for each point I think it can be a good idea to move arcDistance implementation to GeoPoint class.

[bport]

@yeikel if you need extra info let me know

[cbuescher]

Possibly related to https://github.com/elastic/elasticsearch/issues/24946

[jpountz]

Discussed in FixitFriday. It is indeed problematic that it only applies to the first geo-point. We might not want to put them on GeoPoint in order to keep that class lightweight but there is also a possibility of having a whitelisted utility class for such methods.

[bport]

@jpountz Ok thanks for taking care of it, if I can help in any way let me know

[lukas-gitl]

Also very interested in this.

[lukas-gitl]

We are now doing something like this to compute the minimum distance to nested children. Note that you will need to enable include_in_root for the nesting. Enjoy.

double dist=Double.MAX_VALUE; 
for (int i=0; i<doc['venues.location'].values.length; i++) { 
    double lat1 = doc['venues.location'][i].lat;
    double lon1 = doc['venues.location'][i].lon;
    double lat2 = 77.096080;
    double lon2 = 28.51818;
    double TO_METERS = 6371008.7714D;
    double TO_RADIANS = Math.PI / 180D;
    double x1 = lat1 * TO_RADIANS;
    double x2 = lat2 * TO_RADIANS;
    double h1 = 1 - Math.cos(x1 - x2);
    double h2 = 1 - Math.cos((lon1 - lon2) * TO_RADIANS);
    double h = h1 + Math.cos(x1) * Math.cos(x2) * h2;
    double cdist = TO_METERS * 2 * Math.asin(Math.min(1, Math.sqrt(h * 0.5)));
    dist = Math.min(dist, cdist);
}
return dist;

PS: Not proud of this but it works.

[imotov]

Superseded by #24946