geopy distance calculation pitfall

10 December 2007   1 comment   Python

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Geopy is a great little Python library for working with geocoding and distances using various online services such as Google's geocoder API.

Today I spent nearly half an hour trying to debug what was going on with my web application since I was getting this strange error:

AttributeError: 'VincentyDistance' object has no attribute '_kilometers'

To debug it I wrapped the calls to geopy.distance.distance in various try-and-except statements to see what was going on and run these queries in a separate file. After a while I discovered that was what so special about the coordinates I fed it was that the coordinates where the same. Now my wrapping function looks like this instead:

from geopy import distance as geopy_distance
def geocode_distance((x1, y1), (x2, y2), unit='km'):
   if (x1, y1) == (x2, y2):
       return 0
   d = geopy_distance.distance((x1, y1), (x2, y2))
   if unit == 'miles':
       return d.miles
       return d.kilometers

Here's the mailing list thread about the very same issue


python has a great structure but i find it impossible to get used to the infinite number of libraries. for example, this sample code uses geopy so it doesn't run on my system. your link to geopy is broken!

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