Python implementation of the Haversine function to convert GPS coords to kilometers and miles.

gps_haversine.py

def haversine(pos1, pos2):
  # From http://stackoverflow.com/a/18144531/3788069
  lat1 = float(pos1['lat'])
  long1 = float(pos1['long'])
  lat2 = float(pos2['lat'])
  long2 = float(pos2['long'])

  degree_to_rad = float(pi / 180.0)

  d_lat = (lat2 - lat1) * degree_to_rad
  d_long = (long2 - long1) * degree_to_rad

  a = pow(sin(d_lat / 2), 2) + cos(lat1 * degree_to_rad) * cos(lat2 * degree_to_rad) * pow(sin(d_long / 2), 2)
  c = 2 * atan2(sqrt(a), sqrt(1 - a))
  km = 6367 * c
  mi = 3956 * c

  return {"km":km, "miles":mi}