Add method and (failing) test to get instance grouping

sleap/gui/commands.py

@@ -3751,6 +3751,50 @@ def get_all_views_at_frame(
 
         return views
 
+    @staticmethod
+    def get_instance_grouping(
+        instances: Dict[int, Dict[Camcorder, List[Instance]]],
+        reprojection_error_per_frame: Dict[int, float],
+    ) -> Dict[int, Dict[Camcorder, List[Instance]]]:
+        """Get instance grouping for triangulation."""
+
+        frame_with_min_error = min(
+            reprojection_error_per_frame, key=reprojection_error_per_frame.get
+        )
+
+        best_instances = instances[frame_with_min_error]
+        best_instances_correct_format = {frame_with_min_error: best_instances}
+
+        return best_instances_correct_format
+
+    @staticmethod
+    def calculate_reprojection_per_frame(
+        session: RecordingSession, instances: Dict[int, Dict[Camcorder, List[Instance]]]
+    ) -> Dict[int, float]:
+        """Calculate reprojection error per frame."""
+
+        reprojection_error_per_frame = {}
+
+        # Triangulate and reproject instance coordinates.
+        instances_and_coords: Dict[
+            int, Dict[Camcorder, Iterator[Tuple[Instance, np.ndarray]]]
+        ] = TriangulateSession.calculate_reprojected_points(
+            session=session, instances=instances
+        )
+        for frame_id, instances_in_frame in instances_and_coords.items():
+            frame_error = 0
+            for cam, instances_in_view in instances_in_frame.items():
+                # Compare instance coordinates here
+                view_error = 0
+                for inst, inst_coords in instances_in_view:
+                    node_errors = np.nan_to_num(inst.numpy() - inst_coords)
+                    instance_error = np.linalg.norm(node_errors)
+                    view_error += instance_error
+                frame_error += view_error
+            reprojection_error_per_frame[frame_id] = frame_error
+
+        return reprojection_error_per_frame
+
     @staticmethod
     def get_permutations_of_instances(
         selected_instance: Instance,

tests/gui/test_commands.py

@@ -1366,3 +1366,65 @@ def product(seq):
             for inst in instances_in_view:
                 assert inst.frame_idx == selected_instance.frame_idx
                 assert inst.video == session[cam]
+
+
+def test_triangulate_session_calculate_reprojection_per_frame(
+    multiview_min_session_labels: Labels,
+):
+    """Test `TriangulateSession.get_permutations_of_instances`."""
+
+    labels = multiview_min_session_labels
+    session = labels.sessions[0]
+    lf = labels.labeled_frames[0]
+    selected_instance = lf.instances[0]
+
+    instances = TriangulateSession.get_permutations_of_instances(
+        selected_instance=selected_instance,
+        session=session,
+        frame_idx=lf.frame_idx,
+    )
+
+    reprojection_error_per_frame = TriangulateSession.calculate_reprojection_per_frame(
+        session=session, instances=instances
+    )
+
+    for frame_id in instances.keys():
+        assert frame_id in reprojection_error_per_frame
+        assert isinstance(reprojection_error_per_frame[frame_id], float)
+
+
+def test_triangulate_session_get_instance_grouping(
+    multiview_min_session_labels: Labels,
+):
+    """Test `TriangulateSession.get_permutations_of_instances`."""
+
+    labels = multiview_min_session_labels
+    session = labels.sessions[0]
+    lf = labels.labeled_frames[0]
+    selected_instance = lf.instances[0]
+
+    instances = TriangulateSession.get_permutations_of_instances(
+        selected_instance=selected_instance,
+        session=session,
+        frame_idx=lf.frame_idx,
+    )
+
+    reprojection_error_per_frame = TriangulateSession.calculate_reprojection_per_frame(
+        session=session, instances=instances
+    )
+
+    best_instances: Dict[
+        int, Dict[Camcorder, Instance]
+    ] = TriangulateSession.get_instance_grouping(
+        instances=instances, reprojection_error_per_frame=reprojection_error_per_frame
+    )
+    assert len(best_instances) == 1
+    for frame_id, instances_in_frame in best_instances.items():
+        for cam, instances_in_view in instances_in_frame.items():
+            for inst in instances_in_view:
+                assert inst.frame_idx == selected_instance.frame_idx
+                assert inst.track == selected_instance.track
+
+
+if __name__ == "__main__":
+    pytest.main([f"{__file__}::test_triangulate_session_get_instance_grouping"])