Re: locating cities within a radius of another

[Oliver Kohll - Mailing Lists <oliver.lists@xxxxxxxxxx>]

On 22 Jul 2010, at 12:57, Geoffrey wrote:

For completeness, the earthdistance module also provides the distance between two lat/longs, the point<@>point syntax is simple to use:

http://www.postgresql.org/docs/8.3/static/earthdistance.html

Disgregard my last post, Surely as soon as I hit send, the light went on...  I'm looking at deriving my points for point <@> point from ll_to_earth().

I constructed mine using point(longitude, latitude), where long and lat are double precision, which returns a datatype of type point. ll_to_earth() looks like it returns a datatype of type earth, so not sure if it will work. Maybe things have changed in a recent release, please let me know if so.

So an example would be

select point(-2.2171,56.8952)<@>point(-1.2833,51.6667) as miles; 

      miles       

------------------

 363.202864676916

(1 row)

Regards

Oliver Kohll

oliver@xxxxxxxxxxxxxxx / +44(0)7814 828608 / skype:okohll

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