Hi Robert
does anyone know a gem / plugin / class with methods to do calculations
based on lat/lon coordinates? E.g. calculate the distance of 2 points on the earth surface. I tried to implement my own stuff, which does not quite give me exact results.
(quite a repost from a recent railsfrance ML thread, sorry for people subscribing to both lists)
Not specifically a gem for the moment, but you may find the information useful though.
Are you trying to compute bird-flight distances, or driving distances ?
for bird-flight distances:
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if you have access to the Google API, you can rely on “distanceFrom”
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if you don’t, you can rely on the Haversine formula (did you use this very one in your own implementation ?)
=> http://www.movable-type.co.uk/scripts/GIS-FAQ-5.1.html => http://en.wikipedia.org/wiki/Haversine_formula => implementation example here : http://www.supinfo-projects.com/fr/2006/getting%5Fstarted%5Fwith%5Fgoogle%5Fmaps/1/
for driving distances it’s more complicated (and google API doesn’t expose this functionaly AFAIK, although it’s available in maps.google.com
hope this helps
Thibaut
