Distance between list of points based on latitude/longitude

Question

so I have this list of coordinates and I need final SUM of distance between them.

track = [[49.16967, 20.21491, 1343],
        [49.17066, 20.22002, 1373],
        [49.16979, 20.22416, 1408],
        [49.17077, 20.22186, 1422],
        [49.17258, 20.22094, 1467],
        [49.17294, 20.21944, 1460]]

So far I have basic formula for calculating distance between 2 sets of coordinates

import math
def distance(lat_start, lon_start, lat_ciel, lon_ciel):
    R = 6371000
    lat_start = math.radians(lat_start)
    lon_start = math.radians(lon_start)
    lat_ciel = math.radians(lat_ciel)
    lon_ciel = math.radians(lon_ciel)
    DiffLat = lat_ciel - lat_start
    DiffLon = lon_ciel - lon_start
    a = math.sin(DiffLat/2) ** 2 + math.cos(lat_start) * math.cos(lat_ciel) * math.sin(DiffLon / 2) ** 2
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))
    return R * c

I am stuck on the next step, I tried creating a different function that uses existing function for distance and just take each set of coordinates and calculate distance and just add the result numbers together.
Thanks for any help.

Answer 1

import math
from itertools import combinations

def distance(lat_start, lon_start, lat_ciel, lon_ciel):
    R = 6371000
    lat_start = math.radians(lat_start)
    lon_start = math.radians(lon_start)
    lat_ciel = math.radians(lat_ciel)
    lon_ciel = math.radians(lon_ciel)
    DiffLat = lat_ciel - lat_start
    DiffLon = lon_ciel - lon_start
    a = math.sin(DiffLat/2) ** 2 + math.cos(lat_start) * math.cos(lat_ciel) * math.sin(DiffLon / 2) ** 2
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))
    return R * c

def sum_distance(track):
  return sum((map(lambda p: distance(*p[0][:2], *p[1][:2]), combinations(track, 2))))

my_track = [[49.16967, 20.21491, 1343],
        [49.17066, 20.22002, 1373],
        [49.16979, 20.22416, 1408],
        [49.17077, 20.22186, 1422],
        [49.17258, 20.22094, 1467],
        [49.17294, 20.21944, 1460]]

print(sum_distance(my_track))   # 5252.0327870706005

Explanation

1. combinations(...) from https://docs.python.org/2/library/itertools.html#itertools.combinations provides all combinations of pairs
2. lambda p: distance(*p[0][:2], *p[1][:2]) computes distance for a pair, with p[0] and p[1] being the first and second elements of a pair
3. [:2] is a slice to get the first two elements (ie lat/long)
4. *p[x][:2] provides the unpacking of the first two elements for arguments of the distance function
5. map(...) generate distance for all pairs
6. sum(...) sums up the distance of pairs