testing angle operations

skais/ais/ais_trajectory.py

@@ -137,17 +137,26 @@ def compute_position_dist_std(dat, radius):
     return dist_means
 
 
+@jit(nopython=True)
+def angle_between_three_points(p1, p2, p3):
+    alpha = bearing(p2, p1)
+    beta = bearing(p2, p3)
+
+    return alpha - beta
+
+
 def compute_point_angles(dat):
     angles = np.zeros(dat.shape[0])
+
+    p1 = (dat[0][0], dat[0][1])
+    p2 = (dat[1][0], dat[1][1])
+    angles[0] = bearing(p2, p1)
     for i in range(1, dat.shape[0] - 1):
         p1 = (dat[i - 1][0], dat[i - 1][1])
         p2 = (dat[i][0], dat[i][1])
         p3 = (dat[i + 1][0], dat[i + 1][1])
 
-        alpha = bearing(p2, p1)
-        beta = bearing(p2, p3)
-
-        angles[i] = 180 - abs(abs(alpha - beta) - 180)
+        angles[i] = angle_between_three_points(p1, p2, p3)
     return angles
 
 
@@ -182,6 +191,7 @@ def angle_dispersion(dat, radius):
 
     return disp
 
+
 class AISTrajectory:
     def __init__(self, df, interpolation_time=None):
         df = df.drop_duplicates(subset=['ts_sec'])

skais/tests/ais/test_ais_trajectory.py

@@ -4,7 +4,8 @@ import unittest
 import pandas as pd
 import numpy as np
 
-from skais.ais.ais_trajectory import AISTrajectory, compute_std, to_rad, bearing, to_deg, compute_point_angles
+from skais.ais.ais_trajectory import AISTrajectory, compute_std, to_rad, bearing, to_deg, compute_point_angles, \
+    angle_between_three_points
 
 
 class TestAISTrajectory(unittest.TestCase):
@@ -354,6 +355,35 @@ class TestAISTrajectory(unittest.TestCase):
 
         self.assertAlmostEqual(result, expected)
 
+    def test_angle_between_three_points_1(self):
+        p1 = (0, 0)
+        p2 = (0, 10)
+        p3 = (10, 10)
+
+        self.assertEqual(90, angle_between_three_points.py_func(p1, p2, p3))
+
+    def test_angle_between_three_points_2(self):
+        p1 = (0, 0)
+        p2 = (0, 10)
+        p3 = (-10, -10)
+
+        self.assertEqual(-90, angle_between_three_points.py_func(p1, p2, p3))
+
+    def test_angle_between_three_points_3(self):
+        p1 = (0, 0)
+        p2 = (0, 10)
+        p3 = (10, 20)
+
+        self.assertEqual(42.814167, angle_between_three_points.py_func(p1, p2, p3))
+
+    def test_angle_between_three_points_4(self):
+        p1 = (0, 0)
+        p2 = (00, 10)
+        p3 = (0, 0)
+
+        self.assertEqual(180, abs(angle_between_three_points.py_func(p1, p2, p3)))
+
+
     # def test_compute_position_angle_std(self):
     #     dat = [(0, i * 10) for i in range(5)] + [(0, 50 - i * 10) for i in range(5)]
     #     result = compute_position_angle_std(dat, 2)