Fix missing instance frame

dreem/datasets/sleap_dataset.py

@@ -143,7 +143,13 @@ def __init__(
         # for label in self.labels:
         # label.remove_empty_instances(keep_empty_frames=False)
 
-        self.frame_idx = [torch.arange(len(labels)) for labels in self.labels]
+        # note if slp is missing frames, taking last frame idx is safer than len(labels)
+        # as there will be fewer labeledframes than actual frames
+        self.frame_idx = [
+            torch.arange(labels[-1].frame_idx + 1) for labels in self.labels
+        ]
+        self.skipped_frame_ct = [0 for labels in self.labels]
+        # self.frame_idx = [torch.arange(len(labels)) for labels in self.labels]
         # Method in BaseDataset. Creates label_idx and chunked_frame_idx to be
         # used in call to get_instances()
         self.create_chunks()
@@ -168,7 +174,6 @@ def get_instances(self, label_idx: list[int], frame_idx: list[int]) -> list[Fram
 
         """
         video = self.labels[label_idx]
-
         video_name = self.video_files[label_idx]
 
         # get the correct crop size based on the video
@@ -201,7 +206,15 @@ def get_instances(self, label_idx: list[int], frame_idx: list[int]) -> list[Fram
 
             frame_ind = int(frame_ind)
 
-            lf = video[frame_ind]
+            # if slp is missing instances in some frames, frame_ind will be smaller than lf.frame_idx
+            lf = video[frame_ind - self.skipped_frame_ct[label_idx]]
+            if frame_ind < lf.frame_idx:
+                logger.warning(
+                    f"Frame index {frame_ind} is trying to access frame {lf.frame_idx} of the slp file {video_name}. "
+                    f"This likely means there are no labelled instances in this frame. Skipping frame."
+                )
+                self.skipped_frame_ct[label_idx] += 1
+                continue
 
             try:
                 img = vid_reader.get_data(int(lf.frame_idx))