Revert "refactor: Optimize affinity matrix calculation with parallel processing"

This reverts commit e79e899b87.

playground.py

@@ -14,11 +14,7 @@
 
 
 # %%
-## imports
-
-import time
 from collections import OrderedDict
-from concurrent.futures import ThreadPoolExecutor, as_completed
 from copy import copy as shallow_copy
 from copy import deepcopy as deep_copy
 from dataclasses import dataclass
@@ -964,11 +960,9 @@ def calculate_affinity_matrix(
     w_3d: float,
     alpha_3d: float,
     lambda_a: float,
-    max_workers: int | None = None,
 ) -> dict[CameraID, AffinityResult]:
     """
     Calculate the affinity matrix between a set of trackings and detections.
-    Uses parallel processing with ThreadPoolExecutor to handle multiple cameras concurrently.
 
     Args:
         trackings: Sequence of tracking objects
@@ -978,7 +972,6 @@ def calculate_affinity_matrix(
         w_3d: Weight for 3D affinity
         alpha_3d: Normalization factor for 3D distance
         lambda_a: Decay rate for time difference
-        max_workers: Maximum number of parallel workers (threads), None = auto
     Returns:
         A dictionary mapping camera IDs to affinity results.
     """
@@ -987,30 +980,8 @@ def calculate_affinity_matrix(
     else:
         detection_by_camera = classify_by_camera(detections)
 
-    def _single_camera_job(
-        camera_id: CameraID,
-        camera_detections: list[Detection],
-        trackings: Sequence[Tracking],
-        w_2d: float,
-        alpha_2d: float,
-        w_3d: float,
-        alpha_3d: float,
-        lambda_a: float,
-    ) -> tuple[CameraID, AffinityResult]:
-        """
-        Process a single camera's detections to calculate affinity and assignment.
-        This function is designed to be run in parallel for each camera.
-
-        Args:
-            camera_id: The camera ID
-            camera_detections: List of detections from this camera
-            trackings: Sequence of tracking objects
-            w_2d, alpha_2d, w_3d, alpha_3d, lambda_a: Affinity parameters
-
-        Returns:
-            A tuple of (camera_id, AffinityResult)
-        """
-        # 1) Calculate affinity matrix
+    res: dict[CameraID, AffinityResult] = {}
+    for camera_id, camera_detections in detection_by_camera.items():
         affinity_matrix = calculate_camera_affinity_matrix_jax(
             trackings,
             camera_detections,
@@ -1020,37 +991,16 @@ def calculate_affinity_matrix(
             alpha_3d,
             lambda_a,
         )
-        # 2) Calculate assignment
+        # row, col
         indices_T, indices_D = linear_sum_assignment(affinity_matrix)
-        return camera_id, AffinityResult(
+        affinity_result = AffinityResult(
             matrix=affinity_matrix,
             trackings=trackings,
             detections=camera_detections,
             indices_T=indices_T,
             indices_D=indices_D,
         )
-
-    # Run cameras in parallel
-    res: dict[CameraID, AffinityResult] = {}
-    job = partial(
-        _single_camera_job,
-        trackings=trackings,
-        w_2d=w_2d,
-        alpha_2d=alpha_2d,
-        w_3d=w_3d,
-        alpha_3d=alpha_3d,
-        lambda_a=lambda_a,
-    )
-
-    with ThreadPoolExecutor(max_workers=max_workers) as pool:
-        futures = [
-            pool.submit(job, cam_id, cam_dets)
-            for cam_id, cam_dets in detection_by_camera.items()
-        ]
-        for fut in as_completed(futures):
-            cam_id, out = fut.result()
-            res[cam_id] = out
-
+        res[camera_id] = affinity_result
     return res
 
 
@@ -1066,7 +1016,6 @@ trackings = sorted(global_tracking_state.trackings.values(), key=lambda x: x.id)
 unmatched_detections = shallow_copy(next_group)
 camera_detections = classify_by_camera(unmatched_detections)
 
-t0 = time.perf_counter()
 affinities = calculate_affinity_matrix(
     trackings,
     unmatched_detections,
@@ -1077,7 +1026,5 @@ affinities = calculate_affinity_matrix(
     lambda_a=LAMBDA_A,
 )
 display(affinities)
-t1 = time.perf_counter()
-print(f"Time taken: {t1 - t0} seconds")
 
 # %%