libpysal.cg.arcdist

libpysal.cg.arcdist(pt0, pt1, radius=6371.0)[source]

Arc distance between two points on a sphere.

Parameters
pt0point

assumed to be in form (lng,lat)

pt1point

assumed to be in form (lng,lat)

radiusradius of the sphere

defaults to Earth’s radius

Source: http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html

Returns
The arc distance between pt0 and pt1 using supplied radius

Examples

>>> pt0 = (0,0)
>>> pt1 = (180,0)
>>> d = arcdist(pt0,pt1,RADIUS_EARTH_MILES)
>>> d == math.pi*RADIUS_EARTH_MILES
True