Another python haversine implementation

haversines.py

#!/usr/bin/env python

import math

# from here: https://gist.github.com/rochacbruno/2883505
def distance(origin, destination):
    lat1, lon1 = origin
    lat2, lon2 = destination
    radius = 6371 # km
 
    dlat = math.radians(lat2-lat1)
    dlon = math.radians(lon2-lon1)
    a = math.sin(dlat/2) * math.sin(dlat/2) + math.cos(math.radians(lat1)) \
    * math.cos(math.radians(lat2)) * math.sin(dlon/2) * math.sin(dlon/2)
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1-a))
    d = radius * c
 
    return d

# from here: https://github.com/mapado/haversine/blob/master/haversine/__init__.py
def py_haversine(point1, point2, miles=False):
    """ Calculate the great-circle distance bewteen two points on the Earth surface.
        :input: two 2-tuples, containing the latitude and longitude of each point
        in decimal degrees.
        Example: haversine((45.7597, 4.8422), (48.8567, 2.3508))
        :output: Returns the distance bewteen the two points.
        The default unit is kilometers. Miles can be returned
        if the ``miles`` parameter is set to True.
        """
    # unpack latitude/longitude
    lat1, lng1 = point1
    lat2, lng2 = point2
    # convert all latitudes/longitudes from decimal degrees to radians
    lat1, lng1, lat2, lng2 = list(map(math.radians, [lat1, lng1, lat2, lng2]))
    # calculate haversine
    lat = lat2 - lat1
    lng = lng2 - lng1
    d = math.sin(lat / 2) ** 2 + math.cos(lat1) * math.cos(lat2) * math.sin(lng / 2) ** 2
    h = 2 * 6371 * math.asin(math.sqrt(d))
    if miles:
        return h * 0.621371 # in miles
    else:
        return h # in kilometers

def my_hvsin(start, finish, r=6371):
    # convert input tuples to radians
    lat1, lon1 = map(math.radians, start)
    lat2, lon2 = map(math.radians, finish) 
    haversine = lambda x: math.sin(x/2)**2  # define ha(lf-)versine

    # calculate the haversines of the deltas between start and end
    dlat, dlon = (haversine(lat2 - lat1), haversine(lon2 - lon1))
    d = 2*r*math.asin(math.sqrt(dlat + math.cos(lat1) * math.cos(lat2) * dlon))
    return d

# examples
print distance((45.31, 122.40), (47.36, 122.19))
print py_haversine((45.31, 122.40), (47.36, 122.19))
print my_hvsin((45.31, 122.40), (47.36, 122.19))

FYI the function my_hvsin(start,finish,r=6371) should be construed as public domain code.