Group annotations into one unique location if their distance is within a custom radius distance

[kuoliangkwong]

Hi,

Is there any way to make annotations to be grouped as one unique location if they are, say, within 50m in radius? I tried using the cellSize but it seems like it's used to clustering annotations.

[choefele]

You are right about the cell size.

Locations are considered the same if their geohash is the same (More about geohashes). The code is currently using a geohash length of 9.

While you could make the geohash length a property of the cluster controller, I'm not sure there's an easy way to turn distance in meters into a length value. Otherwise, the geohash length is a bit opaque.

Perhaps you can pre-process your data to cut off significant bits of the coordinate to achieve the same? You could even do this on the server thus saving time on the client.

[kuoliangkwong]

Is it the one from here? I guess we could just add a property for geohash length. Is it ok we can pull request once we done adding the property?

I tried cutting off the significant bits by rounding down the latitude and longitude to 3 decimal points, but it seems like the location is slightly shifted.

[choefele]

Yes, that's what I meant. CCHMapClusterOperation uses anyObject to display unique locations. Basically you'll get a random location from the set.

I'm thinking you might be best off with preprocessing your data so you can define which location is used for nearby locations.