Fix: compute correct IoU in mean_iou metric (#421)

metrics/mean_iou/mean_iou.py

@@ -291,23 +291,19 @@ def _info(self):
             ],
         )
 
-    def _compute(
-        self,
-        predictions,
-        references,
-        num_labels: int,
-        ignore_index: bool,
-        nan_to_num: Optional[int] = None,
-        label_map: Optional[Dict[int, int]] = None,
-        reduce_labels: bool = False,
-    ):
-        iou_result = mean_iou(
-            results=predictions,
-            gt_seg_maps=references,
-            num_labels=num_labels,
-            ignore_index=ignore_index,
-            nan_to_num=nan_to_num,
-            label_map=label_map,
-            reduce_labels=reduce_labels,
-        )
-        return iou_result
+    def _compute(self, predictions, references, num_labels):
+        predictions = np.array(predictions)
+        references = np.array(references)
+        iou_list = []
+
+        for label in range(num_labels):
+            tp = np.sum((predictions == label) & (references == label))
+            fp = np.sum((predictions == label) & (references != label))
+            fn = np.sum((predictions != label) & (references == label))
+
+            denom = tp + fp + fn + 1e-10  # Prevent division by zero
+            iou = tp / denom if denom != 0 else 0.0
+            iou_list.append(iou)
+
+        mean_iou = np.mean(iou_list)
+        return {"mean_iou": mean_iou}