baoilleach

import math
import pybel

def sqr_dist(a, b):
    ac = a.coords
    bc = b.coords
    return (ac[0]-bc[0])**2 + (ac[1]-bc[1])**2 + (ac[2]-bc[2])**2

# Definitions taken from
#    http://baoilleach.blogspot.com/2007/07/pybel-hack-that-sd-file.html