Add interpolation test

src/ssoss/process_road_objects.py

@@ -677,6 +677,36 @@ def get_speed_at_timestamp(self, ts):
                 break
         return speed
 
+    def get_location_at_timestamp(self, ts):
+        """Return interpolated :class:`geopy.Point` for a timestamp."""
+
+        point_list = self.gpx_listDF
+        last_point = len(point_list) - 1
+
+        if ts < point_list.loc[0][0].get_timestamp():
+            return None
+        if ts > point_list.loc[last_point][0].get_timestamp():
+            return None
+
+        for i in range(len(point_list) - 1):
+            p_curr = point_list.loc[i][0]
+            p_next = point_list.loc[i + 1][0]
+            t0 = p_curr.get_timestamp()
+            t1 = p_next.get_timestamp()
+            if t0 <= ts <= t1:
+                if t1 == t0:
+                    return p_curr.get_location()
+                ratio = (ts - t0) / (t1 - t0)
+                lat = p_curr.get_location().latitude + ratio * (
+                    p_next.get_location().latitude - p_curr.get_location().latitude
+                )
+                lon = p_curr.get_location().longitude + ratio * (
+                    p_next.get_location().longitude - p_curr.get_location().longitude
+                )
+                return geopy.Point(lat, lon)
+
+        return None
+
 
 
 

tests/test_process_road_objects.py

@@ -0,0 +1,29 @@
+import sys
+import pathlib
+import unittest
+from datetime import datetime, timezone
+
+sys.path.insert(0, str(pathlib.Path(__file__).resolve().parents[1] / "src"))
+
+from ssoss.process_road_objects import ProcessRoadObjects
+from ssoss.motion_road_object import GPXPoint
+import pandas as pd
+
+
+class TestLocationInterpolation(unittest.TestCase):
+    def setUp(self):
+        p0 = GPXPoint(0, datetime.fromtimestamp(0, tz=timezone.utc).isoformat(), (0.0, 0.0), 0)
+        p1 = GPXPoint(1, datetime.fromtimestamp(10, tz=timezone.utc).isoformat(), (0.0, 1.0), 0)
+        self.proc = ProcessRoadObjects()
+        self.proc.gpx_listDF = pd.DataFrame({"gpx_pt": [p0, p1]})
+
+    def test_midpoint_interpolation(self):
+        ts = 5.0
+        location = self.proc.get_location_at_timestamp(ts)
+        self.assertIsNotNone(location)
+        self.assertAlmostEqual(location.latitude, 0.0, places=6)
+        self.assertAlmostEqual(location.longitude, 0.5, places=6)
+
+
+if __name__ == "__main__":
+    unittest.main()