Updates to calculate haversine distance

python/python-examples/pyproject.toml

@@ -9,7 +9,8 @@ authors = [
 requires-python = ">=3.13"
 dependencies = [
     "pydantic",
-    "fastapi"
+    "fastapi",
+    "scikit-learn"
 ]
 
 [dependency-groups]

python/python-examples/src/python_examples/math/haversine_distance.py

@@ -0,0 +1,37 @@
+"""
+Utility class to use python to calculate the haversine distance between two longitude
+and latitude points.
+"""
+import logging as log
+
+from math import radians, sin, cos, atan2, sqrt
+
+log.basicConfig(level=log.INFO)
+
+# Radius of earth in meters
+RADIUS_OF_EARTH = 6371000
+
+def calculate_haversine_distince(lat_long_start:list, lat_long_end:list):
+    """Calculate the haversine distance."""
+    # Taken from here 
+    # https://community.esri.com/t5/coordinate-reference-systems-blog/distance-on-a-sphere-the-haversine-formula/ba-p/902128
+
+    # Direct Unpack the 
+    # Minor correction to code unpack should 
+    lat1, lon1 = lat_long_start
+    lat2, lon2 = lat_long_end
+
+    # Radians???
+    phi_1 = radians(lat1)
+    phi_2 = radians(lat2)
+
+    delta_phi = radians(lat2 - lat1)
+    delta_lambda = radians(lon2 - lon1)
+
+    a = sin(delta_phi / 2.0) ** 2 + cos(phi_1) * cos(phi_2) * sin(delta_lambda / 2.0) ** 2
+    c = 2 * atan2(sqrt(a), sqrt(1 - a))
+
+    # Output distance in meters
+    meters = RADIUS_OF_EARTH * c
+
+    return meters

python/python-examples/test/test_haversine_distance.py

@@ -0,0 +1,31 @@
+"""
+Test for haversine distance.
+"""
+import logging as log
+from math import radians
+import pytest
+from sklearn.metrics.pairwise import haversine_distances
+from python_examples.math.haversine_distance import calculate_haversine_distince, RADIUS_OF_EARTH
+
+@pytest.mark.parametrize("lat_long_origin,lat_long_destination", [
+    # Scikit Learn example Ezeiza Airport -> Charles de Gaulle Airport
+    pytest.param(
+        [-34.83333, -58.5166646], 
+        [49.0083899664, 2.53844117956]
+    )
+])
+def test_calculate_haversince_distance(lat_long_origin:list, lat_long_destination:list):
+    """Test haversine_distance against """
+    # log.info(f"origin:{lat_long_origin} destination:{lat_long_destination}")
+    log.info(f"{lat_long_origin} - {lat_long_destination}")
+    origin_in_radians = [radians(_) for _ in lat_long_origin]
+    destination_in_radians = [radians(_) for _ in lat_long_destination]
+    distance_matrix_result = haversine_distances([origin_in_radians, destination_in_radians])
+    km_distance_matrix_result = distance_matrix_result * RADIUS_OF_EARTH / 1000
+
+    haversine_distance = calculate_haversine_distince(lat_long_origin, lat_long_destination)
+    km_haversine_distance = round(haversine_distance / 1000, 8)
+    sklearn_distance = km_distance_matrix_result[0][1]
+    log.info(f"Raw Calc={km_haversine_distance}, Sklearn Calc={sklearn_distance}")
+    # Rounding both to 8 digits of accuracy...
+    assert km_haversine_distance == round(km_distance_matrix_result[0][1], 8)