utils: Remove unused wgs84_to_sphere

Use an external package[1] instead.

[1]: eg. https://pypi.python.org/pypi/haversine

ogn/utils.py

@@ -1,7 +1,6 @@
 import requests
 import csv
 from io import StringIO
-from math import sin, cos, asin, atan2, sqrt, pi
 
 from .model import Device, AddressOrigin
 
@@ -9,8 +8,6 @@ from geopy.geocoders import Nominatim
 
 DDB_URL = "http://ddb.glidernet.org/download"
 
-deg2rad = pi/180
-rad2deg = 1/deg2rad
 
 address_prefixes = {'F':'FLR',
                     'O':'OGN',
@@ -63,14 +60,3 @@ def get_country_code(latitude, longitude):
     except KeyError:
         country_code = None
     return country_code
-
-
-def wgs84_to_sphere(lat1, lat2, lon1, lon2, alt1, alt2):
-    lat1 = lat1*deg2rad
-    lat2 = lat2*deg2rad
-    lon1 = lon1*deg2rad
-    lon2 = lon2*deg2rad
-    radius = 6366000*2*asin(sqrt((sin((lat1-lat2)/2))**2 + cos(lat1)*cos(lat2)*(sin((lon1-lon2)/2))**2))
-    theta = atan2(alt2-alt1, radius)*rad2deg
-    phi = atan2(sin(lon2-lon1)*cos(lat2), cos(lat1)*sin(lat2)-sin(lat1)*cos(lat2)*cos(lon2-lon1))*rad2deg
-    return radius, theta, phi

tests/test_utils.py

@@ -1,6 +1,6 @@
 import unittest
 
-from ogn.utils import get_ddb, get_trackable, get_country_code, wgs84_to_sphere
+from ogn.utils import get_ddb, get_trackable, get_country_code
 from ogn.model import AddressOrigin
 
 
@@ -43,19 +43,3 @@ class TestStringMethods(unittest.TestCase):
         longitude = -0.0009119
         country_code = get_country_code(latitude, longitude)
         self.assertEqual(country_code, None)
-
-    def test_wgs84_to_sphere(self):
-        # receiver
-        lat1 = 48.865
-        lon1 = 9.2225
-        alt1 = 574
-
-        # aircraft beacon
-        lat2 = 48.74435
-        lon2 = 9.578
-        alt2 = 929
-
-        [radius, theta, phi] = wgs84_to_sphere(lat1, lat2, lon1, lon2, alt1, alt2)
-        self.assertAlmostEqual(radius, 29265.6035812215, 5)
-        self.assertAlmostEqual(theta, 0.694979846308314, 5)
-        self.assertAlmostEqual(phi, 117.1275408121, 5)