python - Looking for a pythonic way to calculate the length of a WKT linestring

I was quite unsatisfied with Calculating Length of Linestrings in WGS84 in Miles. It kept me wondering if there is a more convenient, Pythonic way to calculate the length of a WKT linestring according to a given SRID.

I have in mind something like:

srid="WGS84"

line="LINESTRING(3.0 4.0, 3.1 4.1)"
print length(line, srid)

I'm looking for an accurate answer, not sin\cos approximations.

Any ideas?

Answer

The geopy module provides the Vincenty formula, which provides accurate ellipsoid distances. Couple this with the wkt loading in Shapely, and you have reasonably simple code:

from geopy import distance
from shapely.wkt import loads


line_wkt="LINESTRING(3.0 4.0, 3.1 4.1)"

# a number of other elipsoids are supported
distance.VincentyDistance.ELLIPSOID = 'WGS-84'
d = distance.distance

line = loads(line_wkt)

# convert the coordinates to xy array elements, compute the distance
dist = d(line.xy[0], line.xy[1])


print dist.meters